How to determine equality for two JavaScript objects?

A strict equality operator will tell you if two object types are equal. However, is there a way to tell if two objects are equal, much like the hash code value in Java?

Stack Overflow question Is there any kind of hashCode function in JavaScript? is similar to this question, but requires a more academic answer. The scenario above demonstrates why it would be necessary to have one, and I'm wondering if there is any equivalent solution.

Why reinvent the wheel? Give Lodash a try. It has a number of must-have functions such as isEqual().

_.isEqual(object, other);

It will brute force check each key value - just like the other examples on this page - using ECMAScript 5 and native optimizations if they're available in the browser.

Note: Previously this answer recommended Underscore.js, but lodash has done a better job of getting bugs fixed and addressing issues with consistency.

The short answer

The simple answer is: No, there is no generic means to determine that an object is equal to another in the sense you mean. The exception is when you are strictly thinking of an object being typeless.

The long answer

The concept is that of an Equals method that compares two different instances of an object to indicate whether they are equal at a value level. However, it is up to the specific type to define how an Equals method should be implemented. An iterative comparison of attributes that have primitive values may not be enough: an object may contain attributes which are not relevant to equality. For example,

 function MyClass(a, b)
 {
     var c;
     this.getCLazy = function() {
         if (c === undefined) c = a * b // imagine * is really expensive
         return c;
     }
  }

In this above case, c is not really important to determine whether any two instances of MyClass are equal, only a and b are important. In some cases c might vary between instances and yet not be significant during comparison.

Note this issue applies when members may themselves also be instances of a type and these each would all be required to have a means of determining equality.

Further complicating things is that in JavaScript the distinction between data and method is blurred.

An object may reference a method that is to be called as an event handler, and this would likely not be considered part of its 'value state'. Whereas another object may well be assigned a function that performs an important calculation and thereby makes this instance different from others simply because it references a different function.

What about an object that has one of its existing prototype methods overridden by another function? Could it still be considered equal to another instance that it otherwise identical? That question can only be answered in each specific case for each type.

As stated earlier, the exception would be a strictly typeless object. In which case the only sensible choice is an iterative and recursive comparison of each member. Even then one has to ask what is the 'value' of a function?

The default equality operator in JavaScript for Objects yields true when they refer to the same location in memory.

var x = {};
var y = {};
var z = x;

x === y; // => false
x === z; // => true

If you require a different equality operator you'll need to add an equals(other) method, or something like it to your classes and the specifics of your problem domain will determine what exactly that means.

Here's a playing card example:

function Card(rank, suit) {
  this.rank = rank;
  this.suit = suit;
  this.equals = function(other) {
     return other.rank == this.rank && other.suit == this.suit;
  };
}

var queenOfClubs = new Card(12, "C");
var kingOfSpades = new Card(13, "S");

queenOfClubs.equals(kingOfSpades); // => false
kingOfSpades.equals(new Card(13, "S")); // => true

If you are working in AngularJS, the angular.equals function will determine if two objects are equal. In Ember.js use isEqual.

• angular.equals - See the docs or source for more on this method. It does a deep compare on arrays too.
• Ember.js isEqual - See the docs or source for more on this method. It does not do a deep compare on arrays.

var purple = [{"purple": "drank"}];
var drank = [{"purple": "drank"}];

if(angular.equals(purple, drank)) {
    document.write('got dat');
}

<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.4.5/angular.min.js"></script>

This is my version. It is using new Object.keys feature that is introduced in ES5 and ideas/tests from +, + and +:

function objectEquals(x, y) {
    'use strict';

    if (x === null || x === undefined || y === null || y === undefined) { return x === y; }
    // after this just checking type of one would be enough
    if (x.constructor !== y.constructor) { return false; }
    // if they are functions, they should exactly refer to same one (because of closures)
    if (x instanceof Function) { return x === y; }
    // if they are regexps, they should exactly refer to same one (it is hard to better equality check on current ES)
    if (x instanceof RegExp) { return x === y; }
    if (x === y || x.valueOf() === y.valueOf()) { return true; }
    if (Array.isArray(x) && x.length !== y.length) { return false; }

    // if they are dates, they must had equal valueOf
    if (x instanceof Date) { return false; }

    // if they are strictly equal, they both need to be object at least
    if (!(x instanceof Object)) { return false; }
    if (!(y instanceof Object)) { return false; }

    // recursive object equality check
    var p = Object.keys(x);
    return Object.keys(y).every(function (i) { return p.indexOf(i) !== -1; }) &&
        p.every(function (i) { return objectEquals(x[i], y[i]); });
}


///////////////////////////////////////////////////////////////
/// The borrowed tests, run them by clicking "Run code snippet"
///////////////////////////////////////////////////////////////
var printResult = function (x) {
    if (x) { document.write('<div style="color: green;">Passed</div>'); }
    else { document.write('<div style="color: red;">Failed</div>'); }
};
var assert = { isTrue: function (x) { printResult(x); }, isFalse: function (x) { printResult(!x); } }
assert.isTrue(objectEquals(null,null));
assert.isFalse(objectEquals(null,undefined));
assert.isFalse(objectEquals(/abc/, /abc/));
assert.isFalse(objectEquals(/abc/, /123/));
var r = /abc/;
assert.isTrue(objectEquals(r, r));

assert.isTrue(objectEquals("hi","hi"));
assert.isTrue(objectEquals(5,5));
assert.isFalse(objectEquals(5,10));

assert.isTrue(objectEquals([],[]));
assert.isTrue(objectEquals([1,2],[1,2]));
assert.isFalse(objectEquals([1,2],[2,1]));
assert.isFalse(objectEquals([1,2],[1,2,3]));

assert.isTrue(objectEquals({},{}));
assert.isTrue(objectEquals({a:1,b:2},{a:1,b:2}));
assert.isTrue(objectEquals({a:1,b:2},{b:2,a:1}));
assert.isFalse(objectEquals({a:1,b:2},{a:1,b:3}));

assert.isTrue(objectEquals({1:{name:"mhc",age:28}, 2:{name:"arb",age:26}},{1:{name:"mhc",age:28}, 2:{name:"arb",age:26}}));
assert.isFalse(objectEquals({1:{name:"mhc",age:28}, 2:{name:"arb",age:26}},{1:{name:"mhc",age:28}, 2:{name:"arb",age:27}}));

Object.prototype.equals = function (obj) { return objectEquals(this, obj); };
var assertFalse = assert.isFalse,
    assertTrue = assert.isTrue;

assertFalse({}.equals(null));
assertFalse({}.equals(undefined));

assertTrue("hi".equals("hi"));
assertTrue(new Number(5).equals(5));
assertFalse(new Number(5).equals(10));
assertFalse(new Number(1).equals("1"));

assertTrue([].equals([]));
assertTrue([1,2].equals([1,2]));
assertFalse([1,2].equals([2,1]));
assertFalse([1,2].equals([1,2,3]));
assertTrue(new Date("2011-03-31").equals(new Date("2011-03-31")));
assertFalse(new Date("2011-03-31").equals(new Date("1970-01-01")));

assertTrue({}.equals({}));
assertTrue({a:1,b:2}.equals({a:1,b:2}));
assertTrue({a:1,b:2}.equals({b:2,a:1}));
assertFalse({a:1,b:2}.equals({a:1,b:3}));

assertTrue({1:{name:"mhc",age:28}, 2:{name:"arb",age:26}}.equals({1:{name:"mhc",age:28}, 2:{name:"arb",age:26}}));
assertFalse({1:{name:"mhc",age:28}, 2:{name:"arb",age:26}}.equals({1:{name:"mhc",age:28}, 2:{name:"arb",age:27}}));

var a = {a: 'text', b:[0,1]};
var b = {a: 'text', b:[0,1]};
var c = {a: 'text', b: 0};
var d = {a: 'text', b: false};
var e = {a: 'text', b:[1,0]};
var i = {
    a: 'text',
    c: {
        b: [1, 0]
    }
};
var j = {
    a: 'text',
    c: {
        b: [1, 0]
    }
};
var k = {a: 'text', b: null};
var l = {a: 'text', b: undefined};

assertTrue(a.equals(b));
assertFalse(a.equals(c));
assertFalse(c.equals(d));
assertFalse(a.equals(e));
assertTrue(i.equals(j));
assertFalse(d.equals(k));
assertFalse(k.equals(l));

// from comments on stackoverflow post
assert.isFalse(objectEquals([1, 2, undefined], [1, 2]));
assert.isFalse(objectEquals([1, 2, 3], { 0: 1, 1: 2, 2: 3 }));
assert.isFalse(objectEquals(new Date(1234), 1234));

// no two different function is equal really, they capture their context variables
// so even if they have same toString(), they won't have same functionality
var func = function (x) { return true; };
var func2 = function (x) { return true; };
assert.isTrue(objectEquals(func, func));
assert.isFalse(objectEquals(func, func2));
assert.isTrue(objectEquals({ a: { b: func } }, { a: { b: func } }));
assert.isFalse(objectEquals({ a: { b: func } }, { a: { b: func2 } }));

Short functional deepEqual implementation:

function deepEqual(x, y) {
  return (x && y && typeof x === 'object' && typeof y === 'object') ?
    (Object.keys(x).length === Object.keys(y).length) &&
      Object.keys(x).reduce(function(isEqual, key) {
        return isEqual && deepEqual(x[key], y[key]);
      }, true) : (x === y);
}

Edit: version 2, using jib's suggestion and ES6 arrow functions:

function deepEqual(x, y) {
  const ok = Object.keys, tx = typeof x, ty = typeof y;
  return x && y && tx === 'object' && tx === ty ? (
    ok(x).length === ok(y).length &&
      ok(x).every(key => deepEqual(x[key], y[key]))
  ) : (x === y);
}

If you are using a JSON library, you can encode each object as JSON, then compare the resulting strings for equality.

var obj1={test:"value"};
var obj2={test:"value2"};

alert(JSON.encode(obj1)===JSON.encode(obj2));

NOTE: While this answer will work in many cases, as several people have pointed out in the comments it's problematic for a variety of reasons. In pretty much all cases you'll want to find a more robust solution.

In Node.js, you can use its native require("assert").deepStrictEqual. More info: http://nodejs.org/api/assert.html

For example:

var assert = require("assert");
assert.deepStrictEqual({a:1, b:2}, {a:1, b:3}); // will throw AssertionError

Another example that returns true / false instead of returning errors:

var assert = require("assert");

function deepEqual(a, b) {
    try {
      assert.deepEqual(a, b);
    } catch (error) {
      if (error.name === "AssertionError") {
        return false;
      }
      throw error;
    }
    return true;
};

Are you trying to test if two objects are the equal? ie: their properties are equal?

If this is the case, you'll probably have noticed this situation:

var a = { foo : "bar" };
var b = { foo : "bar" };
alert (a == b ? "Equal" : "Not equal");
// "Not equal"

you might have to do something like this:

function objectEquals(obj1, obj2) {
    for (var i in obj1) {
        if (obj1.hasOwnProperty(i)) {
            if (!obj2.hasOwnProperty(i)) return false;
            if (obj1[i] != obj2[i]) return false;
        }
    }
    for (var i in obj2) {
        if (obj2.hasOwnProperty(i)) {
            if (!obj1.hasOwnProperty(i)) return false;
            if (obj1[i] != obj2[i]) return false;
        }
    }
    return true;
}

Obviously that function could do with quite a bit of optimisation, and the ability to do deep checking (to handle nested objects: var a = { foo : { fu : "bar" } }) but you get the idea.

As FOR pointed out, you might have to adapt this for your own purposes, eg: different classes may have different definitions of "equal". If you're just working with plain objects, the above may suffice, otherwise a custom MyClass.equals() function may be the way to go.

For those of you using Node, there is a convenient method called isDeepStrictEqual on the nativeutil library that can achieve this.

const util = require('util');

const obj1 = {
  foo: "bar",
  baz: [1, 2]
};

const obj2 = {
  foo: "bar",
  baz: [1, 2]
};


obj1 == obj2 // false
util.isDeepStrictEqual(obj1, obj2) // true

https://nodejs.org/api/util.html#util_util_isdeepstrictequal_val1_val2

If you have a deep copy function handy, you can use the following trick to still use JSON.stringify while matching the order of properties:

function equals(obj1, obj2) {
    function _equals(obj1, obj2) {
        return JSON.stringify(obj1)
            === JSON.stringify($.extend(true, {}, obj1, obj2));
    }
    return _equals(obj1, obj2) && _equals(obj2, obj1);
}

Demo: http://jsfiddle.net/CU3vb/3/

Rationale:

Since the properties of obj1 are copied to the clone one by one, their order in the clone will be preserved. And when the properties of obj2 are copied to the clone, since properties already existing in obj1 will simply be overwritten, their orders in the clone will be preserved.

Simplest and logical solutions for comparing everything Like Object, Array, String, Int...

JSON.stringify({a: val1}) === JSON.stringify({a: val2})

Note:

• you need to replace val1and val2 with your Object
• for the object, you have to sort(by key) recursively for both side objects

var object1 = {name: "humza" , gender : "male", age: 23}
var object2 = {name: "humza" , gender : "male", age: 23}
var result = Object.keys(object1).every((key) =>  object1[key] === object2[key])

Result will be true if object1 has same values on object2.

This question has more than 30 answers already. I am going to summarize and explain them (with a "my father" analogy) and add my suggested solution.

You have 4+1 classes of solutions:

---

1) Use a hacky incomplete quick one-liner

Good if you are in a rush and 99% correctness works.

Examples of this is, JSON.stringify() suggested by Pratik Bhalodiya, or JSON.encode by Joel Anair, or .toString(), or other methods that transform your objects into a String and then compare the two Strings using === character by character.

The drawback, however, is that there is no globally standard unique representation of an Object in String. e.g. { a: 5, b: 8} and {b: 8 and a: 5 } are equal.

• Pros: Fast, quick.
• Cons: Hopefully works! It will not work if the environment/browser/engine memorizes the ordering for objects (e.g. Chrome/V8) and the order of the keys are different (Thanks to Eksapsy.) So, not guaranteed at all. Performance wouldn't be great either in large objects.

My Father Analogy

When I am talking about my father, "my tall handsome father" and "my handsome tall father" are the same person! But the two strings are not the same.

Note that there is actually a correct (standard way) order of adjectives in English grammar, which says it should be a "handsome tall man," but you are risking your competency if you blindly assume Javascript engine of iOS 8 Safari is also abiding the same grammar, blindly! #WelcomeToJavascriptNonStandards

---

2) Write your own DIY recursive function

Good if you are learning.

Examples are atmin's solution.

The biggest disadvantage is you will definitely miss some edge cases. Have you considered a self-reference in object values? Have you considered NaN? Have you considered two objects that have the same ownProperties but different prototypical parents?

I would only encourage people to do this if they are practicing and the code is not going to go in production. That's the only case that reinventing the wheel has justifications.

• Pros: Learning opportunity.
• Cons: Not reliable. Takes time and concerns.

My Father Analogy

It's like assuming if my dad's name is "John Smith" and his birthday is "1/1/1970", then anyone whose name is "John Smith" and is born on "1/1/1970" is my father.

That's usually the case, but what if there are two "John Smith"s born on that day? If you think you will consider their height, then that's increasing the accuracy but still not a perfect comparison.

2.1 You limited scope DIY comparator

Rather than going on a wild chase of checking all the properties recursively, one might consider checking only "a limited" number of properties. For instance, if the objects are Users, you can compare their emailAddress field.

It's still not a perfect one, but the benefits over solution #2 are:

1. It's predictable, and it's less likely to crash.
2. You are driving the "definition" of equality, rather than relying on a wild form and shape of the Object and its prototype and nested properties.

---

3) Use a library version of equal function

Good if you need a production-level quality, and you cannot change the design of the system.

Examples are _.equal of lodash, already in coolaj86's answer or Angular's or Ember's as mentioned in Tony Harvey's answer or Node's by Rafael Xavier.

• Pros: It's what everyone else does.
• Cons: External dependency, which can cost you extra memory/CPU/Security concerns, even a little bit. Also, can still miss some edge cases (e.g. whether two objects having same ownProperties but different prototypical parents should be considered the same or not.) Finally, you might be unintentionally band-aiding an underlying design problem with this; just saying!

My Father Analogy

It's like paying an agency to find my biological father, based on his phone, name, address, etc.

It's gonna cost more, and it's probably more accurate than myself running the background check, but doesn't cover edge cases like when my father is immigrant/asylum and his birthday is unknown!

---

4) Use an IDentifier in the Object

Good if you [still] can change the design of the system (objects you are dealing with) and you want your code to last long.

It's not applicable in all cases, and might not be very performant. However, it's a very reliable solution, if you can make it.

The solution is, every object in the system will have a unique identifier along with all the other properties. The uniqueness of the identifier will be guaranteed at the time of generation. And you will use this ID (also known as UUID/GUID -- Globally/Universally Unique Identifier) when it comes to comparing two objects. i.e. They are equal if and only if these IDs are equal.

The IDs can be simple auto_incremental numbers, or a string generated via a library (advised) or a piece of code. All you need to do is make sure it's always unique, which in case of auto_incremental it can be built-in, or in case of UUID, can be checked will all existing values (e.g. MySQL's UNIQUE column attribute) or simply (if coming from a library) be relied upon giving the extremely low likelihood of a collision.

Note that you also need to store the ID with the object at all times (to guarantee its uniqueness), and computing it in real-time might not be the best approach.

• Pros: Reliable, efficient, not dirty, modern.
• Cons: Needs extra space. Might need a redesign of the system.

My Father Analogy

It's like known my father's Social Security Number is 911-345-9283, so anyone who has this SSN is my father, and anyone who claims to be my father must have this SSN.

---

Conclusion

I personally prefer solution #4 (ID) over them all for accuracy and reliability. If it's not possible I'd go with #2.1 for predictability, and then #3. If neither is possible, #2 and finally #1.

I use this comparable function to produce copies of my objects that are JSON comparable:

var comparable = o => (typeof o != 'object' || !o)? o :
  Object.keys(o).sort().reduce((c, key) => (c[key] = comparable(o[key]), c), {});

// Demo:

var a = { a: 1, c: 4, b: [2, 3], d: { e: '5', f: null } };
var b = { b: [2, 3], c: 4, d: { f: null, e: '5' }, a: 1 };

console.log(JSON.stringify(comparable(a)));
console.log(JSON.stringify(comparable(b)));
console.log(JSON.stringify(comparable(a)) == JSON.stringify(comparable(b)));

<div id="div"></div>

Comes in handy in tests (most test frameworks have an is function). E.g.

is(JSON.stringify(comparable(x)), JSON.stringify(comparable(y)), 'x must match y');

If a difference is caught, strings get logged, making differences spottable:

x must match y
got      {"a":1,"b":{"0":2,"1":3},"c":7,"d":{"e":"5","f":null}},
expected {"a":1,"b":{"0":2,"1":3},"c":4,"d":{"e":"5","f":null}}.

Heres's a solution in ES6/ES2015 using a functional-style approach:

const typeOf = x => 
  ({}).toString
      .call(x)
      .match(/\[object (\w+)\]/)[1]
    
function areSimilar(a, b) {
  const everyKey = f => Object.keys(a).every(f)

  switch(typeOf(a)) {
    case 'Array':
      return a.length === b.length &&
        everyKey(k => areSimilar(a.sort()[k], b.sort()[k]));
    case 'Object':
      return Object.keys(a).length === Object.keys(b).length &&
        everyKey(k => areSimilar(a[k], b[k]));
    default:
      return a === b;
  }
}

demo available here

I don't know if anyone's posted anything similar to this, but here's a function I made to check for object equalities.

function objectsAreEqual(a, b) {
  for (var prop in a) {
    if (a.hasOwnProperty(prop)) {
      if (b.hasOwnProperty(prop)) {
        if (typeof a[prop] === 'object') {
          if (!objectsAreEqual(a[prop], b[prop])) return false;
        } else {
          if (a[prop] !== b[prop]) return false;
        }
      } else {
        return false;
      }
    }
  }
  return true;
}

Also, it's recursive, so it can also check for deep equality, if that's what you call it.

ES6: The minimum code I could get it done, is this. It do deep comparison recursively by stringifying all key value array sorted representing the object, the only limitation is no methods or symbols are compare.

const compareObjects = (a, b) => { 
  let s = (o) => Object.entries(o).sort().map(i => { 
     if(i[1] instanceof Object) i[1] = s(i[1]);
     return i 
  }) 
  return JSON.stringify(s(a)) === JSON.stringify(s(b))
}

console.log(compareObjects({b:4,a:{b:1}}, {a:{b:1},b:4}));

IMPORTANT: This function is doing a JSON.stringfy in an ARRAY with the keys sorted and NOT in the object it self:

1. ["a", ["b", 1]]
2. ["b", 4]

EDIT: This method is quite flawed, and is rife with its own issues. I don't recommend it, and would appreciate some down-votes! It is problematic because 1) Some things can not be compared (i.e. functions) because they can not be serialized, 2) It isn't a very fast method of comparing, 3) It has ordering issues, 4) It can have collision issues/false positives if not properly implemented, 5) It can't check for "exactness" (===), and instead is based of value equality, which is oftentimes not what is desired in a comparison method.

A simple solution to this issue that many people don't realize is to sort the JSON strings (per character). This is also usually faster than the other solutions mentioned here:

function areEqual(obj1, obj2) {
    var a = JSON.stringify(obj1), b = JSON.stringify(obj2);
    if (!a) a = '';
    if (!b) b = '';
    return (a.split('').sort().join('') == b.split('').sort().join(''));
}

Another useful thing about this method is you can filter comparisons by passing a "replacer" function to the JSON.stringify functions (https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/JSON/stringify#Example_of_using_replacer_parameter). The following will only compare all objects keys that are named "derp":

function areEqual(obj1, obj2, filter) {
    var a = JSON.stringify(obj1, filter), b = JSON.stringify(obj2, filter);
    if (!a) a = '';
    if (!b) b = '';
    return (a.split('').sort().join('') == b.split('').sort().join(''));
}
var equal = areEqual(obj1, obj2, function(key, value) {
    return (key === 'derp') ? value : undefined;
});

Just wanted to contribute my version of objects comparison utilizing some es6 features. It doesn't take an order into account. After converting all if/else's to ternary I've came with following:

function areEqual(obj1, obj2) {

    return Object.keys(obj1).every(key => {

            return obj2.hasOwnProperty(key) ?
                typeof obj1[key] === 'object' ?
                    areEqual(obj1[key], obj2[key]) :
                obj1[key] === obj2[key] :
                false;

        }
    )
}

you can use _.isEqual(obj1, obj2) from the underscore.js library.

Here is an example:

var stooge = {name: 'moe', luckyNumbers: [13, 27, 34]};
var clone  = {name: 'moe', luckyNumbers: [13, 27, 34]};
stooge == clone;
=> false
_.isEqual(stooge, clone);
=> true

See the official documentation from here: http://underscorejs.org/#isEqual

Assuming that the order of the properties in the object is not changed.

JSON.stringify() works for deep and non-deep both types of objects, not very sure of performance aspects:

var object1 = {
  key: "value"
};

var object2 = {
  key: "value"
};

var object3 = {
  key: "no value"
};

console.log('object1 and object2 are equal: ', JSON.stringify(object1) === JSON.stringify(object2));

console.log('object2 and object3 are equal: ', JSON.stringify(object2) === JSON.stringify(object3));

Below is a short implementation which uses JSON.stringify but sorts the keys as @Jor suggested here.

Some tests were taken from the answer of @EbrahimByagowi here.

Of course, by using JSON.stringify, the solution is limited to JSON-serializable types (a string, a number, a JSON object, an array, a boolean, null). Objects like Date, Function, etc. are not supported.

function objectEquals(obj1, obj2) {
  const JSONstringifyOrder = obj => {
    const keys = {};
    JSON.stringify(obj, (key, value) => {
      keys[key] = null;
      return value;
    });
    return JSON.stringify(obj, Object.keys(keys).sort());
  };
  return JSONstringifyOrder(obj1) === JSONstringifyOrder(obj2);
}

///////////////////////////////////////////////////////////////
/// The borrowed tests, run them by clicking "Run code snippet"
///////////////////////////////////////////////////////////////
var printResult = function (x) {
    if (x) { document.write('<div style="color: green;">Passed</div>'); }
    else { document.write('<div style="color: red;">Failed</div>'); }
};
var assert = { isTrue: function (x) { printResult(x); }, isFalse: function (x) { printResult(!x); } }

assert.isTrue(objectEquals("hi","hi"));
assert.isTrue(objectEquals(5,5));
assert.isFalse(objectEquals(5,10));

assert.isTrue(objectEquals([],[]));
assert.isTrue(objectEquals([1,2],[1,2]));
assert.isFalse(objectEquals([1,2],[2,1]));
assert.isFalse(objectEquals([1,2],[1,2,3]));

assert.isTrue(objectEquals({},{}));
assert.isTrue(objectEquals({a:1,b:2},{a:1,b:2}));
assert.isTrue(objectEquals({a:1,b:2},{b:2,a:1}));
assert.isFalse(objectEquals({a:1,b:2},{a:1,b:3}));

assert.isTrue(objectEquals({1:{name:"mhc",age:28}, 2:{name:"arb",age:26}},{1:{name:"mhc",age:28}, 2:{name:"arb",age:26}}));
assert.isFalse(objectEquals({1:{name:"mhc",age:28}, 2:{name:"arb",age:26}},{1:{name:"mhc",age:28}, 2:{name:"arb",age:27}}));

Needing a more generic object comparison function than had been posted, I cooked up the following. Critique appreciated...

Object.prototype.equals = function(iObj) {
  if (this.constructor !== iObj.constructor)
    return false;
  var aMemberCount = 0;
  for (var a in this) {
    if (!this.hasOwnProperty(a))
      continue;
    if (typeof this[a] === 'object' && typeof iObj[a] === 'object' ? !this[a].equals(iObj[a]) : this[a] !== iObj[a])
      return false;
    ++aMemberCount;
  }
  for (var a in iObj)
    if (iObj.hasOwnProperty(a))
      --aMemberCount;
  return aMemberCount ? false : true;
}

If you are comparing JSON objects you can use https://github.com/mirek/node-rus-diff

npm install rus-diff

Usage:

a = {foo:{bar:1}}
b = {foo:{bar:1}}
c = {foo:{bar:2}}

var rusDiff = require('rus-diff').rusDiff

console.log(rusDiff(a, b)) // -> false, meaning a and b are equal
console.log(rusDiff(a, c)) // -> { '$set': { 'foo.bar': 2 } }

If two objects are different, a MongoDB compatible {$rename:{...}, $unset:{...}, $set:{...}} like object is returned.

I faced the same problem and deccided to write my own solution. But because I want to also compare Arrays with Objects and vice-versa, I crafted a generic solution. I decided to add the functions to the prototype, but one can easily rewrite them to standalone functions. Here is the code:

Array.prototype.equals = Object.prototype.equals = function(b) {
    var ar = JSON.parse(JSON.stringify(b));
    var err = false;
    for(var key in this) {
	    if(this.hasOwnProperty(key)) {
		    var found = ar.find(this[key]);
		    if(found > -1) {
			    if(Object.prototype.toString.call(ar) === "[object Object]") {
				    delete ar[Object.keys(ar)[found]];
			    }
			    else {
				    ar.splice(found, 1);
			    }
		    }
		    else {
			    err = true;
			    break;
		    }
	    }
    };
    if(Object.keys(ar).length > 0 || err) {
	    return false;
    }
    return true;
}

Array.prototype.find = Object.prototype.find = function(v) {
    var f = -1;
    for(var i in this) {
	    if(this.hasOwnProperty(i)) {
		    if(Object.prototype.toString.call(this[i]) === "[object Array]" || Object.prototype.toString.call(this[i]) === "[object Object]") {
			    if(this[i].equals(v)) {
				    f = (typeof(i) == "number") ? i : Object.keys(this).indexOf(i);
			    }
		    }
		    else if(this[i] === v) {
			    f = (typeof(i) == "number") ? i : Object.keys(this).indexOf(i);
		    }
	    }
    }
    return f;
}

This Algorithm is split into two parts; The equals function itself and a function to find the numeric index of a property in an array / object. The find function is only needed because indexof only finds numbers and strings and no objects .

One can call it like this:

({a: 1, b: "h"}).equals({a: 1, b: "h"});

The function either returns true or false, in this case true. The algorithm als allows comparison between very complex objects:

({a: 1, b: "hello", c: ["w", "o", "r", "l", "d", {answer1: "should be", answer2: true}]}).equals({b: "hello", a: 1, c: ["w", "d", "o", "r", {answer1: "should be", answer2: true}, "l"]})

The upper example will return true, even tho the properties have a different ordering. One small detail to look out for: This code also checks for the same type of two variables, so "3" is not the same as 3.

let std1 = {
  name: "Abhijeet",
  roll: 1
}

let std2 = {
  name: "Siddharth",
  roll: 2
}

console.log(JSON.stringify(std1) === JSON.stringify(std2))

I'd advise against hashing or serialization (as the JSON solution suggest). If you need to test if two objects are equal, then you need to define what equals means. It could be that all data members in both objects match, or it could be that must the memory locations match (meaning both variables reference the same object in memory), or may be that only one data member in each object must match.

Recently I developed an object whose constructor creates a new id (starting from 1 and incrementing by 1) each time an instance is created. This object has an isEqual function that compares that id value with the id value of another object and returns true if they match.

In that case I defined "equal" as meaning the the id values match. Given that each instance has a unique id this could be used to enforce the idea that matching objects also occupy the same memory location. Although that is not necessary.

It's useful to consider two objects equal if they have all the same values for all properties and recursively for all nested objects and arrays. I also consider the following two objects equal:

var a = {p1: 1};
var b = {p1: 1, p2: undefined};

Similarly, arrays can have "missing" elements and undefined elements. I would treat those the same as well:

var c = [1, 2];
var d = [1, 2, undefined];

A function that implements this definition of equality:

function isEqual(a, b) {
    if (a === b) {
        return true;
    }

    if (generalType(a) != generalType(b)) {
        return false;
    }

    if (a == b) {
        return true;
    }

    if (typeof a != 'object') {
        return false;
    }

    // null != {}
    if (a instanceof Object != b instanceof Object) {
        return false;
    }

    if (a instanceof Date || b instanceof Date) {
        if (a instanceof Date != b instanceof Date ||
            a.getTime() != b.getTime()) {
            return false;
        }
    }

    var allKeys = [].concat(keys(a), keys(b));
    uniqueArray(allKeys);

    for (var i = 0; i < allKeys.length; i++) {
        var prop = allKeys[i];
        if (!isEqual(a[prop], b[prop])) {
            return false;
        }
    }
    return true;
}

Source code (including the helper functions, generalType and uniqueArray): Unit Test and Test Runner here.

I'm making the following assumptions with this function:

1. You control the objects you are comparing and you only have primitive values (ie. not nested objects, functions, etc.).
2. Your browser has support for Object.keys.

This should be treated as a demonstration of a simple strategy.

/**
 * Checks the equality of two objects that contain primitive values. (ie. no nested objects, functions, etc.)
 * @param {Object} object1
 * @param {Object} object2
 * @param {Boolean} [order_matters] Affects the return value of unordered objects. (ex. {a:1, b:2} and {b:2, a:1}).
 * @returns {Boolean}
 */
function isEqual( object1, object2, order_matters ) {
    var keys1 = Object.keys(object1),
        keys2 = Object.keys(object2),
        i, key;

    // Test 1: Same number of elements
    if( keys1.length != keys2.length ) {
        return false;
    }

    // If order doesn't matter isEqual({a:2, b:1}, {b:1, a:2}) should return true.
    // keys1 = Object.keys({a:2, b:1}) = ["a","b"];
    // keys2 = Object.keys({b:1, a:2}) = ["b","a"];
    // This is why we are sorting keys1 and keys2.
    if( !order_matters ) {
        keys1.sort();
        keys2.sort();
    }

    // Test 2: Same keys
    for( i = 0; i < keys1.length; i++ ) {
        if( keys1[i] != keys2[i] ) {
            return false;
        }
    }

    // Test 3: Values
    for( i = 0; i < keys1.length; i++ ) {
        key = keys1[i];
        if( object1[key] != object2[key] ) {
            return false;
        }
    }

    return true;
}

For comparing keys for simple key/value pairs object instances, I use:

function compareKeys(r1, r2) {
    var nloops = 0, score = 0;
    for(k1 in r1) {
        for(k2 in r2) {
            nloops++;
            if(k1 == k2)
                score++; 
        }
    }
    return nloops == (score * score);
};

Once keys are compared, a simple additional for..in loop is enough.

Complexity is O(N*N) with N is the number of keys.

I hope/guess objects I define won't hold more than 1000 properties...

This is an addition for all the above, not a replacement. If you need to fast shallow-compare objects without need to check extra recursive cases. Here is a shot.

This compares for: 1) Equality of number of own properties, 2) Equality of key names, 3) if bCompareValues == true, Equality of corresponding property values and their types (triple equality)

var shallowCompareObjects = function(o1, o2, bCompareValues) {
	var s, 
		n1 = 0,
		n2 = 0,
		b  = true;
		
	for (s in o1) { n1 ++; }
	for (s in o2) { 
		if (!o1.hasOwnProperty(s)) {
			b = false;
			break;
		}
		if (bCompareValues && o1[s] !== o2[s]) {
			b = false;
			break;
		}
		n2 ++;
	}
	return b && n1 == n2;
}

I know this is a bit old, but I would like to add a solution that I came up with for this problem. I had an object and I wanted to know when its data changed. "something similar to Object.observe" and what I did was:

function checkObjects(obj,obj2){
   var values = [];
   var keys = [];
   keys = Object.keys(obj);
   keys.forEach(function(key){
      values.push(key);
   });
   var values2 = [];
   var keys2 = [];
   keys2 = Object.keys(obj2);
   keys2.forEach(function(key){
      values2.push(key);
   });
   return (values == values2 && keys == keys2)
}

This here can be duplicated and create an other set of arrays to compare the values and keys. It is very simple because they are now arrays and will return false if objects have different sizes.

Pulling out from my personal library, which i use for my work repeatedly. The following function is a lenient recursive deep equal, which does not check

• Class equality
• Inherited values
• Values strict equality

I mainly use this to check if i get equal replies against various API implementation. Where implementation difference (like string vs number) and additional null values, can occur.

Its implementation is quite straightforward and short (if all the comments is stripped off)

/** Recursively check if both objects are equal in value
***
*** This function is designed to use multiple methods from most probable 
*** (and in most cases) valid, to the more regid and complex method.
***
*** One of the main principles behind the various check is that while
*** some of the simpler checks such as == or JSON may cause false negatives,
*** they do not cause false positives. As such they can be safely run first.
***
*** # !Important Note:
*** as this function is designed for simplified deep equal checks it is not designed
*** for the following
***
*** - Class equality, (ClassA().a = 1) maybe valid to (ClassB().b = 1)
*** - Inherited values, this actually ignores them
*** - Values being strictly equal, "1" is equal to 1 (see the basic equality check on this)
*** - Performance across all cases. This is designed for high performance on the
***   most probable cases of == / JSON equality. Consider bench testing, if you have
***   more 'complex' requirments
***
*** @param  objA : First object to compare
*** @param  objB : 2nd object to compare
*** @param  .... : Any other objects to compare
***
*** @returns true if all equals, or false if invalid
***
*** @license Copyright by [email protected], 2012.
***          Licensed under the MIT license: http://opensource.org/licenses/MIT
**/
function simpleRecusiveDeepEqual(objA, objB) {
	// Multiple comparision check
	//--------------------------------------------
	var args = Array.prototype.slice.call(arguments);
	if(args.length > 2) {
		for(var a=1; a<args.length; ++a) {
			if(!simpleRecusiveDeepEqual(args[a-1], args[a])) {
				return false;
			}
		}
		return true;
	} else if(args.length < 2) {
		throw "simpleRecusiveDeepEqual, requires atleast 2 arguments";
	}
	
	// basic equality check,
	//--------------------------------------------
	// if this succed the 2 basic values is equal,
	// such as numbers and string.
	//
	// or its actually the same object pointer. Bam
	//
	// Note that if string and number strictly equal is required
	// change the equality from ==, to ===
	//
	if(objA == objB) {
		return true;
	}
	
	// If a value is a bsic type, and failed above. This fails
	var basicTypes = ["boolean", "number", "string"];
	if( basicTypes.indexOf(typeof objA) >= 0 || basicTypes.indexOf(typeof objB) >= 0 ) {
		return false;
	}
	
	// JSON equality check,
	//--------------------------------------------
	// this can fail, if the JSON stringify the objects in the wrong order
	// for example the following may fail, due to different string order:
	//
	// JSON.stringify( {a:1, b:2} ) == JSON.stringify( {b:2, a:1} )
	//
	if(JSON.stringify(objA) == JSON.stringify(objB)) {
		return true;
	}
	
	// Array equality check
	//--------------------------------------------
	// This is performed prior to iteration check,
	// Without this check the following would have been considered valid
	//
	// simpleRecusiveDeepEqual( { 0:1963 }, [1963] );
	//
	// Note that u may remove this segment if this is what is intended
	//
	if( Array.isArray(objA) ) {
		//objA is array, objB is not an array
		if( !Array.isArray(objB) ) {
			return false;
		}
	} else if( Array.isArray(objB) ) {
		//objA is not array, objB is an array
		return false;
	}
	
	// Nested values iteration
	//--------------------------------------------
	// Scan and iterate all the nested values, and check for non equal values recusively
	//
	// Note that this does not check against null equality, remove the various "!= null"
	// if this is required
	
	var i; //reuse var to iterate
	
	// Check objA values against objB
	for (i in objA) {
		//Protect against inherited properties
		if(objA.hasOwnProperty(i)) {
			if(objB.hasOwnProperty(i)) {
				// Check if deep equal is valid
				if(!simpleRecusiveDeepEqual( objA[i], objB[i] )) {
					return false;
				}
			} else if(objA[i] != null) {
				//ignore null values in objA, that objB does not have
				//else fails
				return false;
			}
		}
	}
	
	// Check if objB has additional values, that objA do not, fail if so
	for (i in objB) {
		if(objB.hasOwnProperty(i)) {
			if(objB[i] != null && !objA.hasOwnProperty(i)) {
				//ignore null values in objB, that objA does not have
				//else fails
				return false;
			}
		}
	}
	
	// End of all checks
	//--------------------------------------------
	// By reaching here, all iteration scans have been done.
	// and should have returned false if it failed
	return true;
}

// Sanity checking of simpleRecusiveDeepEqual
(function() {
	if(
		// Basic checks
		!simpleRecusiveDeepEqual({}, {}) ||
		!simpleRecusiveDeepEqual([], []) ||
		!simpleRecusiveDeepEqual(['a'], ['a']) ||
		// Not strict checks
		!simpleRecusiveDeepEqual("1", 1) ||
		// Multiple objects check
		!simpleRecusiveDeepEqual( { a:[1,2] }, { a:[1,2] }, { a:[1,2] } ) ||
		// Ensure distinction between array and object (the following should fail)
		simpleRecusiveDeepEqual( [1963], { 0:1963 } ) ||
		// Null strict checks
		simpleRecusiveDeepEqual( 0, null ) ||
		simpleRecusiveDeepEqual( "", null ) ||
		// Last "false" exists to make the various check above easy to comment in/out
		false
	) {
		alert("FATAL ERROR: simpleRecusiveDeepEqual failed basic checks");
	} else { 
		//added this last line, for SO snippet alert on success
		alert("simpleRecusiveDeepEqual: Passed all checks, Yays!");
	}
})();

I see spaghetti code answers. Without using any third party libs, this is very easy.

Firstly sort the two objects by key their key names.

let objectOne = { hey, you }
let objectTwo = { you, hey }

// If you really wanted you could make this recursive for deep sort.
const sortObjectByKeyname = (objectToSort) => {
    return Object.keys(objectToSort).sort().reduce((r, k) => (r[k] = objectToSort[k], r), {});
}

let objectOne = sortObjectByKeyname(objectOne)
let objectTwo = sortObjectByKeyname(objectTwo)

Then simply use a string to compare them.

JSON.stringify(objectOne) === JSON.stringify(objectTwo)

How to determine that the partial object (Partial<T>) is equal to the original object (T) in typescript.

function compareTwoObjects<T>(original: T, partial: Partial<T>): boolean {
  return !Object.keys(partial).some((key) => partial[key] !== original[key]);
}

P.S. Initially I was planning to create a new question with an answer. But such a question already exists and marked as a duplicate.

Here is a solution using ES6+

// this comparison would not work for function and symbol comparisons
// this would only work best for compared objects that do not belong to same address in memory
// Returns true if there is no difference, and false otherwise


export const isObjSame = (obj1, obj2) => {
    if (typeof obj1 !== "object" && obj1 !== obj2) {
        return false;
    }

    if (typeof obj1 !== "object" && typeof obj2 !== "object" && obj1 === obj2) {
        return true;
    }

    if (typeof obj1 === "object" && typeof obj2 === "object") {
        if (Array.isArray(obj1) && Array.isArray(obj2)) {
            if (obj1.length === obj2.length) {
                if (obj1.length === 0) {
                    return true;
                }
                const firstElemType = typeof obj1[0];

                if (typeof firstElemType !== "object") {
                    const confirmSameType = currentType =>
                        typeof currentType === firstElemType;

                    const checkObjOne = obj1.every(confirmSameType);
                    const checkObjTwo = obj2.every(confirmSameType);

                    if (checkObjOne && checkObjTwo) {
                        // they are primitves, we can therefore sort before and compare by index
                        // use number sort
                        // use alphabet sort
                        // use regular sort
                        if (firstElemType === "string") {
                            obj1.sort((a, b) => a.localeCompare(b));
                            obj2.sort((a, b) => a.localeCompare(b));
                        }
                        obj1.sort((a, b) => a - b);
                        obj2.sort((a, b) => a - b);

                        let equal = true;

                        obj1.map((element, index) => {
                            if (!isObjSame(element, obj2[index])) {
                                equal = false;
                            }
                        });

                        return equal;
                    }

                    if (
                        (checkObjOne && !checkObjTwo) ||
                        (!checkObjOne && checkObjTwo)
                    ) {
                        return false;
                    }

                    if (!checkObjOne && !checkObjTwo) {
                        for (let i = 0; i <= obj1.length; i++) {
                            const compareIt = isObjSame(obj1[i], obj2[i]);
                            if (!compareIt) {
                                return false;
                            }
                        }

                        return true;
                    }

                    // if()
                }
                const newValue = isObjSame(obj1, obj2);
                return newValue;
            } else {
                return false;
            }
        }

        if (!Array.isArray(obj1) && !Array.isArray(obj2)) {
            let equal = true;
            if (obj1 && obj2) {
                const allKeys1 = Array.from(Object.keys(obj1));
                const allKeys2 = Array.from(Object.keys(obj2));

                if (allKeys1.length === allKeys2.length) {
                    allKeys1.sort((a, b) => a - b);
                    allKeys2.sort((a, b) => a - b);

                    allKeys1.map((key, index) => {
                        if (
                            key.toLowerCase() !== allKeys2[index].toLowerCase()
                        ) {
                            equal = false;
                            return;
                        }

                        const confirmEquality = isObjSame(obj1[key], obj2[key]);

                        if (!confirmEquality) {
                            equal = confirmEquality;
                            return;
                        }
                    });
                }
            }

            return equal;

            // return false;
        }
    }
};

Although this question is sufficiently answered, I am missing one approach: the toJSON interface.

Usually you want to compare to object by stringifying them, because this is the fastest way. But ofter the comparison is considered to by false, because of the order of the properties.

const obj1 = {
  a: 1,
  b: 2,
  c: { 
    ca: 1,
    cb: 2
  }
}

const obj2 = {
  b: 2, // changed order with a
  a: 1,
  c: { 
    ca: 1,
    cb: 2
  }
}

JSON.stringify(obj1) === JSON.stringify(obj2) // false

Obviously the objects are considered to be different, because the order of property a and b differ.

To solve this, you can implement the toJSON interface, and define a deterministic output.

const obj1 = {
  a: 1,
  b: 2,
  c: { 
    ca: 1,
    cb: 2
  },
  toJSON() {
    return {
      a: this.a,
      b: this.b,
      c: { 
        ca: this.c.ca,
        cb: this.c.ca
      }
    }
  }
}

const obj2 = {
  b: 2,
  a: 1,
  c: { 
    ca: 1,
    cb: 2
  },
  toJSON() {
    return {
      a: this.a,
      b: this.b,
      c: { 
        ca: this.c.ca,
        cb: this.c.ca
      }
    }
  }
}

JSON.stringify(obj1) === JSON.stringify(obj2) // true

Et voila: the string representations of obj1 and obj2 are concidered the same.

TIP

If you do not have access to the direct generation of the object, you can simply attach the toJSON function:

obj1.toJSON = function() {
  return {
    a: this.a,
    b: this.b,
    c: { 
      ca: this.c.ca,
      cb: this.c.ca
    }
  }
}

obj2.toJSON = function() {
  return {
    a: this.a,
    b: this.b,
    c: { 
      ca: this.c.ca,
      cb: this.c.ca
    }
  }
}

JSON.stringify(obj1) === JSON.stringify(obj2) // true

stringify both objects and compare

if(JSON.stringify(object1) == JSON.stringify(object2))
{
true if both same object
}
else
{
false if not same object
}

I'm not a Javascript expert, but here is one simple attempt to solve it. I check for three things:

1. Is it an object and also that it is not null because typeof null is object.
2. If the property count of the two objects is the same? If not they are not equal.
3. Loop through properties of one and check if corresponding property has same value in second object.

function deepEqual (first, second) {
  // Not equal if either is not an object or is null.
  if (!isObject(first) || !isObject(second) ) return false;

  // If properties count is different
  if (keys(first).length != keys(second).length) return false;

  // Return false if any property value is different.
  for(prop in first){
    if (first[prop] != second[prop]) return false;
  }
  return true;
}

// Checks if argument is an object and is not null
function isObject(obj) {
  return (typeof obj === "object" && obj != null);
}

// returns arrays of object keys
function keys (obj) {
  result = [];
  for(var key in obj){
    result.push(key);
  }
  return result;
}

// Some test code
obj1 = {
  name: 'Singh',
  age: 20
}

obj2 = {
  age: 20,
  name: 'Singh'
}

obj3 = {
  name: 'Kaur',
  age: 19
}

console.log(deepEqual(obj1, obj2));
console.log(deepEqual(obj1, obj3));

After so much of searches, i have found following working solution

function isEquivalent(a, b) {
   // Create arrays of property names
   var aProps = Object.getOwnPropertyNames(a);
   var bProps = Object.getOwnPropertyNames(b);

  // If number of properties is different, objects are not equivalent
  if (aProps.length != bProps.length) {
     return false;
  }

  for (var i = 0; i < aProps.length; i++) {
     var propName = aProps[i];

    // If values of same property are not equal, objects are not equivalent
     if (a[propName] !== b[propName]) {
         return false;
     }
  }

// If we made it this far, objects are considered equivalent
return true; }

For more info: Object Equality in JavaScript

I just wrote this method just to be sure that arrays and objects are both compared in a clear way.

This should do the trick as well! :)

public class Objects {
    /**
     * Checks whether a value is of type Object
     * @param value the value
     */
    public static isObject = (value: any): boolean => {
        return value === Object(value) && Object.prototype.toString.call(value) !== '[object Array]'
    }

    /**
     * Checks whether a value is of type Array
     * @param value the value
     */
    public static isArray = (value: any): boolean => {
        return Object.prototype.toString.call(value) === '[object Array]' && !Objects.isObject(value)
    }

    /**
     * Check whether two values are equal
     */
    public static isEqual = (objectA: any, objectB: any) => {
        // Objects
        if (Objects.isObject(objectA) && !Objects.isObject(objectB)) {
            return false
        }
        else if (!Objects.isObject(objectA) && Objects.isObject(objectB)) {
            return false
        }
        // Arrays
        else if (Objects.isArray(objectA) && !Objects.isArray(objectB)) {
            return false
        }
        else if (!Objects.isArray(objectA) && Objects.isArray(objectB)) {
            return false
        }
        // Primitives
        else if (!Objects.isArray(objectA) && !Objects.isObject(objectA)) {
            return objectA === objectB
        }
        // Object or array
        else {
            const compareObject = (objectA: any, objectB: any): boolean => {
                if (Object.keys(objectA).length !== Object.keys(objectB).length) return false

                for (const propertyName of Object.keys(objectA)) {
                    const valueA = objectA[propertyName]
                    const valueB = objectB[propertyName]

                    if (!Objects.isEqual(valueA, valueB)) {
                        return false
                    }
                }

                return true
            }
            const compareArray = (arrayA: any[], arrayB: any[]): boolean => {
                if (arrayA.length !== arrayB.length) return false
                
                for (const index in arrayA) {
                    const valueA = arrayA[index]
                    const valueB = arrayB[index]
                    
                    if (!Objects.isEqual(valueA, valueB)) {
                        return false
                    }
                }

                return true
            }
            if (Objects.isObject(objectA)) {
                return compareObject(objectA, objectB)
            } else {
                return compareArray(objectA, objectB)
            }
        }
    }
}

In objects (without methods) we need to check for nested Objects, Arrays and primitive types. Objects can have other oblects and arrays (arrays also can include other objects and arrays), so we can use recursive function like in below: arrayEquals checks arrays for equality and equals checks objects equality:

function arrayEquals(a, b) {
    if (a.length != b.length) {
        return false;
    }
    for (let i = 0; i < a.length; i++) {
        if (a[i].constructor !== b[i].constructor) {
            return false;
        }

        if (a[i] instanceof Array && b[i] instanceof Array) {
            if (!arrayEquals(a, b)) {
                return false;
            }
        } else if (a[i] instanceof Object && b[i] instanceof Object) {
            if (!equals(a[i], b[i])) {
                return false;
            }
        } else if (a[i] !== b[i]) {
            return false;
        }
    }
    return true;
}

function equals(a, b) {
    for (let el in a) {
        if (b.hasOwnProperty(el)) {
            if (a[el].constructor !== b[el].constructor) {
                return false;
            }

            if (a[el] instanceof Array && b[el] instanceof Array) {
                if (!arrayEquals(a[el], b[el])) {
                    return false;
                }
            } else if (a[el] instanceof Object && b[el] instanceof Object) {
                if (!equals(a[el], b[el])) {
                    return false;
                }
            } else if (a[el] !== b[el]) {
                return false;
            }
        } else {
            return false;
        }
    }
    return true;
}

Imagine you have two objects:

let a = {
    a: 1,
    b: { c: 1, d: "test" },
    c: 3,
    d: [{ a: [1, 2], e: 2 }, "test", { c: 3, q: 5 }],
};

let b = {
    a: 1,
    b: { c: 1, d: "test" },
    c: 3,
    d: [{ a: [1, 2], e: 2 }, "test", { c: 3, q: 5 }],
};

And here using above equals function, you can easily compare two of these objects like this:

if(equals(a, b)) {
    // do whatever you want
}

In React, you can use isEqual from 'react-fast-compare'. This answer is probably not applicable to plain JavaScript, but can be useful in case you are using React.

console.log(isEqual({ hello: 'world' }, { hello: 'world' })) // returns true

> The fastest deep equal comparison for React. Very quick general-purpose deep comparison, too. Great for React.memo and shouldComponentUpdate.

More information can be found here: https://www.npmjs.com/package/react-fast-compare.

One easy way I have found to compare the values of two javascript objects while ignoring property order is with the JSON stringify replacer function:

const compareReplacer = (key, value) => {
	if(typeof value === 'object' && !(value instanceof Array))
  	    return Object.entries(value).sort();
	return value;
}
export const compareObjects = (a, b) => JSON.stringify(a, compareReplacer) === JSON.stringify(b, compareReplacer);

This will order the properties at every step of the way so that the string result will be invariant to property order. Some one has probably done this before but I just thought I would share it incase not :).

2022:

I came up with a breeze dead-simple algorithm that addresses the most edge cases.

Steps:

1. flatten the objects
2. simple compare the two flattened objects and look for differences

If you saved the flatted object you can repeat using it.

let obj1= {var1:'value1', var2:{ var1:'value1', var2:'value2'}};
let obj2 = {var1:'value1', var2:{ var1:'value11',var2:'value2'}} 

let flat1= flattenObject(obj1)
/*
{
 'var1':'value1',
 'var2.var1':'value1',
 'var2.var2':'value2'
}
*/
let flat2= flattenObject(obj2)
/*
{
 'var1':'value1',
 'var2.var1':'value11',
 'var2.var2':'value2'
}
*/
isEqual(flat1, flat2)
/*
 false
*/

of course you can come with your implementations for that steps. but here is mine:

Implementations

function flattenObject(obj) {
 const object = Object.create(null);
 const path = [];
 const isObject = (value) => Object(value) === value;

 function dig(obj) {
  for (let [key, value] of Object.entries(obj)) {
    path.push(key);
    if (isObject(value)) dig(value);
    else object[path.join('.')] = value;
    path.pop();
  }
 }

 dig(obj);
 return object;
}

 function isEqual(flat1, flat2) {
    for (let key in flat2) {
        if (flat1[key] !== flat2[key])
            return false
    }
    // check for missing keys
    for (let key in flat1) {
        if (!(key in flat2))
            return false
    }
    return true
}

You can use that method to also get the Diff object between obj1 and obj2.

Look at that answer for details: Generic deep diff between two objects

Depends on what you mean by equality. And therefore it is up to you, as the developer of the classes, to define their equality.

There's one case used sometimes, where two instances are considered 'equal' if they point to the same location in memory, but that is not always what you want. For instance, if I have a Person class, I might want to consider two Person objects 'equal' if they have the same Last Name, First Name, and Social Security Number (even if they point to different locations in memory).

On the other hand, we can't simply say that two objects are equal if the value of each of their members is the same, since, sometimes, you don't want that. In other words, for each class, it's up to the class developer to define what members make up the objects 'identity' and develop a proper equality operator (be it via overloading the == operator or an Equals method).

Saying that two objects are equal if they have the same hash is one way out. However you then have to wonder how the hash is calculated for each instance. Going back to the Person example above, we could use this system if the hash was calculated by looking at the values of the First Name, Last Name, and Social Security Number fields. On top of that, we are then relying on the quality of the hashing method (that's a huge topic on its own, but suffice it to say that not all hashes are created equal, and bad hashing methods can lead to more collisions, which in this case would return false matches).

A quick "hack" to tell if two objects are similar, is to use their toString() methods. If you're checking objects A and B, make sure A and B have meaningful toString() methods and check that the strings they return are the same.

This isn't a panacea, but it can be useful sometimes in the right situations.

Here is a very basic approach to checking an object's "value equality".

var john = {
    occupation: "Web Developer",
    age: 25
};

var bobby = {
    occupation: "Web Developer",
    age: 25
};

function isEquivalent(a, b) {
    // Create arrays of property names

    var aProps = Object.getOwnPropertyNames(a);
    var bProps = Object.getOwnPropertyNames(b);

    // If number of properties is different, objects are not equivalent

    if (aProps.length != bProps.length) {
        return false;
    }

    for (var i = 0; i < aProps.length; i++) {
        var propName = aProps[i];

        // If values of same property are not equal, objects are not equivalent
        if (a[propName] !== b[propName]) {
           return false;
        }
    }

    // If we made it this far, objects are considered equivalent
    return true;
}

// Outputs: true
console.log(isEquivalent(john, bobby));

Demo - JSFiddle

As you can see, to check the objects' "value equality" we essentially have to iterate over every property in the objects to see whether they are equal. And while this simple implementation works for our example, there are a lot of cases that it doesn't handle. For instance:

• What if one of the property values is itself an object?
• What if one of the property values is NaN (the only value in JavaScript that is not equal to itself?)
• What if a has a property with value undefined, while b doesn't have this property (which thus evaluates to undefined?)

For a robust method of checking objects' "value equality" it is better to rely on a well-tested library that covers the various edge cases like Underscore.

var john = {
    occupation: "Web Developer",
    age: 25
};

var bobby = {
    occupation: "Web Developer",
    age: 25
};

// Outputs: true
console.log(_.isEqual(john, bobby));

Demo - JSFiddle

My version, which includes the chain of where the difference is found, and what the difference is.

function DeepObjectCompare(O1, O2)
{
	try {
		DOC_Val(O1, O2, ['O1->O2', O1, O2]);
		return DOC_Val(O2, O1, ['O2->O1', O1, O2]);
	} catch(e) {
		console.log(e.Chain);
		throw(e);
	}
}
function DOC_Error(Reason, Chain, Val1, Val2)
{
	this.Reason=Reason;
	this.Chain=Chain;
	this.Val1=Val1;
	this.Val2=Val2;
}

function DOC_Val(Val1, Val2, Chain)
{
	function DoThrow(Reason, NewChain) { throw(new DOC_Error(Reason, NewChain!==undefined ? NewChain : Chain, Val1, Val2)); }

	if(typeof(Val1)!==typeof(Val2))
		return DoThrow('Type Mismatch');
	if(Val1===null || Val1===undefined)
		return Val1!==Val2 ? DoThrow('Null/undefined mismatch') : true;
	if(Val1.constructor!==Val2.constructor)
		return DoThrow('Constructor mismatch');
	switch(typeof(Val1))
	{
		case 'object':
			for(var m in Val1)
			{
				if(!Val1.hasOwnProperty(m))
					continue;
				var CurChain=Chain.concat([m]);
				if(!Val2.hasOwnProperty(m))
					return DoThrow('Val2 missing property', CurChain);
				DOC_Val(Val1[m], Val2[m], CurChain);
			}
			return true;
		case 'number':
			if(Number.isNaN(Val1))
				return !Number.isNaN(Val2) ? DoThrow('NaN mismatch') : true;
		case 'string':
		case 'boolean':
			return Val1!==Val2 ? DoThrow('Value mismatch') : true;
		case 'function':
			if(Val1.prototype!==Val2.prototype)
				return DoThrow('Prototype mismatch');
			if(Val1!==Val2)
				return DoThrow('Function mismatch');
			return true;
		default:
			return DoThrow('Val1 is unknown type');
	}
}

I've implemented a method that takes two jsons and checks to see if their keys have the same values using recursion. I used another question to solve this.

const arraysEqual = (a, b) => {
    if (a === b)
        return true;
    if (a === null || b === null)
        return false;
    if (a.length !== b.length)
        return false;

    // If you don't care about the order of the elements inside
    // the array, you should sort both arrays here.

    for (let i = 0; i < a.length; ++i) {
        if (a[i] !== b[i])
            return false;
    }
    return true;
};

const jsonsEqual = (a, b) => {

  if(typeof a !== 'object' || typeof b !== 'object')
      return false;

  if (Object.keys(a).length === Object.keys(b).length) { // if items have the same size
      let response = true;

      for (let key in a) {
          if (!b[key]) // if not key
              response = false;
          if (typeof a[key] !== typeof b[key]) // if typeof doesn't equals
              response = false;
          else {
              if (Array.isArray(a[key])) // if array
                  response = arraysEqual(a[key], b[key]);
              else if (typeof a[key] === 'object') // if another json
                  response = jsonsEqual(a[key], b[key]);
              else if (a[key] !== b[key])  // not equals
                  response = false;
          }
          if (!response) // return if one item isn't equal
              return false;
      }
  } else
      return false;

  return true;
};

const json1 = { 
  a: 'a', 
  b: 'asd', 
  c: [
    '1',
    2,
    2.5,
    '3', 
    {
      d: 'asd',
      e: [
        1.6,
        { 
          f: 'asdasd',
          g: '123'
        }
      ]
    }
  ],
  h: 1,
  i: 1.2,
};

const json2 = {
  a: 'nops',
  b: 'asd'
};

const json3 = { 
  a: 'h', 
  b: '484', 
  c: [
    3,
    4.5,
    '2ss', 
    {
      e: [
        { 
          f: 'asdasd',
          g: '123'
        }
      ]
    }
  ],
  h: 1,
  i: 1.2,
};

const result = jsonsEqual(json1,json2);
//const result = jsonsEqual(json1,json3);
//const result = jsonsEqual(json1,json1);

if(result) // is equal
  $('#result').text("Jsons are the same")
else
  $('#result').text("Jsons aren't equals")

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>

<div id="result"></div>

Here's a version of the stringify trick that is less typing and works in a lot of cases for trivial JSON data comparisons.

var obj1Fingerprint = JSON.stringify(obj1).replace(/\{|\}/g,'').split(',').sort().join(',');
var obj2Fingerprint = JSON.stringify(obj2).replace(/\{|\}/g,'').split(',').sort().join(',');
if ( obj1Fingerprint === obj2Fingerprint) { ... } else { ... }

Lot's of good thoughts here! Here is my version of deep equal. I posted it on github and wrote some tests around it. It's hard to cover all the possible cases and sometimes it's unnecessary to do so.

I covered NaN !== NaN as well as circular dependencies.

https://github.com/ryancat/simple-deep-equal/blob/master/index.js

Depending. If the order of keys in the object are not of importance, and I don't need to know the prototypes of the said object. Using always do the job.

const object = {};
JSON.stringify(object) === "{}" will pass but {} === "{}" will not

This is a simple Javascript function to compare two objects having simple key-value pairs. The function will return an array of strings, where each string is a path to an inequality between the two objects.

function compare(a,b) {
    var paths = [];
    [...new Set(Object.keys(a).concat(Object.keys(b)))].forEach(key=>{
        if(typeof a[key] === 'object' && typeof b[key] === 'object') {
            var results = compare(a[key], b[key]);
            if(JSON.stringify(results)!=='[]') {
                paths.push(...results.map(result=>key.concat("=>"+result)));
            }
        }
        else if (a[key]!==b[key]) {
            paths.push(key);
        }
    })
    return paths;
}

If you only want to compare two objects without knowing the paths to inequalities, you can do it as follows:

if(JSON.stringify(compare(object1, object2))==='[]') {
   // the two objects are equal
} else {
   // the two objects are not equal
}

1. sort the objects (dictionary)

2. compare JSON string

    function areTwoDictsEqual(dictA, dictB) {
        function sortDict(dict) {
            var keys = Object.keys(dict);
            keys.sort();
   
            var newDict = {};
            for (var i=0; i<keys.length; i++) {
                var key = keys[i];
                var value = dict[key];
                newDict[key] = value;
            } 
            return newDict;
        }
   
        return JSON.stringify(sortDict(dictA)) == JSON.stringify(sortDict(dictB));
    }
   

One additional option, is use equals of https://ramdajs.com/docs/#equals">Ramda library:

const c = {a: 1, b: 2};
const d = {b: 2, a: 1};
R.equals(c, d); //=> true

const obj = {
  name: "Carl",
  age: 15
}
const obj2 = {
  name: "Carl",
  age: 15,
}


const compareObj = (objects) => {
  const res =  objects.map((item) => {
    return Object.entries(item).flat().join()
  })
  return res.every((a) => {
    return a === res[0]
  })
}

console.log(compareObj([obj,obj2]))

if u really want to compare and return difference from the two objects. you can use this package: https://www.npmjs.com/package/deep-diff

or just use the code this package used

https://github.com/flitbit/diff/blob/master/index.js

just don't convert it into string to compare.

Pure JS approach: My answer is based on generating a string which returns the same value whether the attribute order is same or not. The settings object can be used to switch whether the case and the presence of white space matters. (To avoid losing focus I'm not including those support functions, or the isObject which I guess should be in any utility set.)

Also not shown here, but to reduce the string comparison time, if the objects are large and you want to speed up the comparison, you could also hash the strings and compare substrings; this would make sense to do only for very large objects (and of course a small chance of false equality).

You can then just compare genObjStr(obj1) ?= genObjStr(obj2)

function genObjStr(obj, settings) {
// Generate a string that corresponds to an object guarenteed to be the same str even if
// the object have different ordering. The string would largely be used for comparison purposes

var settings = settings||{};
var doStripWhiteSpace = defTrue(settings.doStripWhiteSpace);
var doSetLowerCase = settings.doSetLowerCase||false;

if(isArray(obj)) {
    var vals = [];
    for(var i = 0; i < obj.length; ++i) {
        vals.push(genObjStr(obj[i], settings));
    }
    vals = arraySort(vals);
    return vals.join(`,`);

} else if(isObject(obj)) {

    var keys = Object.keys(obj);
    keys = arraySort(keys);

    var vals = [];
    for(var key of keys) {
        
        var value = obj[key];
        
        value = genObjStr(value, settings);

        if(doStripWhiteSpace) {
            key = removeWhitespace(key);
            var value = removeWhitespace(value);
        };
        if(doSetLowerCase) {
            key = key.toLowerCase();
            value = value.toLowerCase();
        }

        vals.push(value);
    }
    var str = JSON.stringify({keys: keys, vals: vals});
    return str
} else {
    if(doStripWhiteSpace) {
        obj = removeWhitespace(obj);
    };
    if(doSetLowerCase) {
        obj = obj.toLowerCase();
    }
    return obj
}

}

var obj1 = {foo: 123, bar: `Test`};
var obj2 = {bar: `Test`, foo: 123};

console.log(genObjStr(obj1) == genObjStr(obj1))

if your question is to check if two objects are equal then this function might be useful

function equals(a, b) {
const aKeys = Object.keys(a)
const bKeys = Object.keys(b)
if(aKeys.length != bKeys.length) {
	return false
}
for(let i = 0;i < aKeys.length;i++) {
	if(aKeys[i] != bKeys[i]) {
		return false
	} 
}
for(let i = 0;i < aKeys.length;i++) {
	if(a[aKeys[i]] != b[bKeys[i]]) {
		return false
	}
}
return true
}

first we check if the length of the list of keys of these objects is the same, if not we return false to check if two objects are equal they must have the same keys(=names) and the same values of the keys, so we get all the keys of objA, and objB and then we check if they are equal once we find that tow keys are not equal then we return false and then when all the keys are equal then we loop through one of the keys of one of the objects and then we check if they are equal once they are not we return false and after the two loops finished this means they are equal and we return true NOTE: this function works with only objects with no functions

> Using JSON.stringify() is not always reliable. So this method is the best solution to your question IMO

First of all, No, there is no generic means to determine that an object is equal!

But there is a concept called Shallow Equality Comparison. There is an npm library out there that can help you use this concept

Example

const shallowequal = require('shallowequal');
 
const object = { 'user': 'fred' };
const other = { 'user': 'fred' };

// Referential Equality Comparison (`strict ===`)
object === other; // → false

// Shallow Equality Comparison
shallowequal(object, other); // → true

If you want to know how to create shallowEqual comparision method, then refer here. Its from the opensource fbjs Facebook library.

---

Shallow Equality Comparision

shallowequal(obj1, obj2)

>shallowEqual Performs a shallow equality comparison between two values (i.e. obj1 and obj2) to determine if they are equivalent.

The equality is performed by iterating through keys on the given obj1, and returning false whenever any key has values which are not strictly equal between obj1 and obj2. Otherwise, return true whenever the values of all keys are strictly equal.

I need to mock jQuery POST requests, so the equality that matters to me is that both objects have the same set of properties (none missing in either object), and that each property value is "equal" (according to this definition). I don't care about the objects having mismatching methods.

Here's what I'll be using, it should be good enough for my specific requirements:

function PostRequest() {
    for (var i = 0; i < arguments.length; i += 2) {
        this[arguments[i]] = arguments[i+1];
    }

    var compare = function(u, v) {
        if (typeof(u) != typeof(v)) {
            return false;
        }

        var allkeys = {};
        for (var i in u) {
            allkeys[i] = 1;
        }
        for (var i in v) {
            allkeys[i] = 1;
        }
        for (var i in allkeys) {
            if (u.hasOwnProperty(i) != v.hasOwnProperty(i)) {
                if ((u.hasOwnProperty(i) && typeof(u[i]) == 'function') ||
                    (v.hasOwnProperty(i) && typeof(v[i]) == 'function')) {
                    continue;
                } else {
                    return false;
                }
            }
            if (typeof(u[i]) != typeof(v[i])) {
                return false;
            }
            if (typeof(u[i]) == 'object') {
                if (!compare(u[i], v[i])) {
                    return false;
                }
            } else {
                if (u[i] !== v[i]) {
                    return false;
                }
            }
        }

        return true;
    };

    this.equals = function(o) {
        return compare(this, o);
    };

    return this;
}

Use like so:

foo = new PostRequest('text', 'hello', 'html', '<p>hello</p>');
foo.equals({ html: '<p>hello</p>', text: 'hello' });

I've written a small library that runs on Node.js and the browser called compare.js. It offers the usual comparison operators, such as ==, !=, >, >=, <, <= and identity on all data types of JavaScript.

E.g., you can use

cmp.eq(obj1, obj2);

and this will check for equality (using a deep-equal approach). Otherwise, if you do

cmp.id(obj1, obj2);

it will compare by reference, hence check for identity. You can also use < and > on objects, which mean subset and superset.

compare.js is covered by nearly 700 unit tests, hence it should hopefully not have too many bugs ;-).

You can find it on https://github.com/goloroden/compare.js for free, it is open-sourced under the MIT license.

Some of the following solutions have problems with performance, functionality and style... They are not thought through enough, and some of them fail for different cases. I tried to address this problem in my own solution, and I would really much appreciate your feedback:

http://stamat.wordpress.com/javascript-object-comparison/

//Returns the object's class, Array, Date, RegExp, Object are of interest to us
var getClass = function(val) {
	return Object.prototype.toString.call(val)
		.match(/^\[object\s(.*)\]$/)[1];
};

//Defines the type of the value, extended typeof
var whatis = function(val) {

	if (val === undefined)
		return 'undefined';
	if (val === null)
		return 'null';

	var type = typeof val;

	if (type === 'object')
		type = getClass(val).toLowerCase();

	if (type === 'number') {
		if (val.toString().indexOf('.') > 0)
			return 'float';
		else
		return 'integer';
	}

	return type;
   };

var compareObjects = function(a, b) {
	if (a === b)
		return true;
	for (var i in a) {
		if (b.hasOwnProperty(i)) {
			if (!equal(a[i],b[i])) return false;
		} else {
			return false;
		}
	}

	for (var i in b) {
		if (!a.hasOwnProperty(i)) {
			return false;
		}
	}
	return true;
};

var compareArrays = function(a, b) {
	if (a === b)
		return true;
	if (a.length !== b.length)
		return false;
	for (var i = 0; i < a.length; i++){
		if(!equal(a[i], b[i])) return false;
	};
	return true;
};

var _equal = {};
_equal.array = compareArrays;
_equal.object = compareObjects;
_equal.date = function(a, b) {
	return a.getTime() === b.getTime();
};
_equal.regexp = function(a, b) {
	return a.toString() === b.toString();
};
//	uncoment to support function as string compare
//	_equal.fucntion =  _equal.regexp;



/*
 * Are two values equal, deep compare for objects and arrays.
 * @param a {any}
 * @param b {any}
 * @return {boolean} Are equal?
 */
var equal = function(a, b) {
	if (a !== b) {
		var atype = whatis(a), btype = whatis(b);

		if (atype === btype)
			return _equal.hasOwnProperty(atype) ? _equal[atype](a, b) : a==b;

		return false;
	}

	return true;
};

Object equality check:JSON.stringify(array1.sort()) === JSON.stringify(array2.sort())

The above test also works with arrays of objects in which case use a sort function as documented in http://www.w3schools.com/jsref/jsref_sort.asp

Might suffice for small arrays with flat JSON schemas.

Sure, while we're at it I'll throw in my own reinvention of the wheel (I'm proud of the number of spokes and materials used):

////////////////////////////////////////////////////////////////////////////////

var equals = function ( objectA, objectB ) {
	var result = false,
		keysA,
		keysB;

	// Check if they are pointing at the same variable. If they are, no need to test further.
	if ( objectA === objectB ) {
		return true;
	}

	// Check if they are the same type. If they are not, no need to test further.
	if ( typeof objectA !== typeof objectB ) {
		return false;
	}

	// Check what kind of variables they are to see what sort of comparison we should make.
	if ( typeof objectA === "object" ) {
		// Check if they have the same constructor, so that we are comparing apples with apples.
		if ( objectA.constructor === objectA.constructor ) {
			// If we are working with Arrays...
			if ( objectA instanceof Array ) {
				// Check the arrays are the same length. If not, they cannot be the same.
				if ( objectA.length === objectB.length ) {
					// Compare each element. They must be identical. If not, the comparison stops immediately and returns false.
					return objectA.every(
						function ( element, i ) {
							return equals( element, objectB[ i ] );
						}
					);
				}
				// They are not the same length, and so are not identical.
				else {
					return false;
				}
			}
			// If we are working with RegExps...
			else if ( objectA instanceof RegExp ) {
				// Return the results of a string comparison of the expression.
				return ( objectA.toString() === objectB.toString() );
			}
			// Else we are working with other types of objects...
			else {
				// Get the keys as arrays from both objects. This uses Object.keys, so no old browsers here.
				keysA = Object.keys( objectA );
		
				keysB = Object.keys( objectB );
		
				// Check the key arrays are the same length. If not, they cannot be the same.
				if ( keysA.length === keysB.length ) {
					// Compare each property. They must be identical. If not, the comparison stops immediately and returns false.
					return keysA.every(
						function ( element ) {
							return equals( objectA[ element ], objectB[ element ] );
						}
					);
				}
				// They do not have the same number of keys, and so are not identical.
				else {
					return false;
				}
			}
		}
		// They don't have the same constructor.
		else {
			return false;
		}
	}
	// If they are both functions, let us do a string comparison.
	else if ( typeof objectA === "function" ) {
		return ( objectA.toString() === objectB.toString() );
	}
	// If a simple variable type, compare directly without coercion.
	else {
		return ( objectA === objectB );
	}

	// Return a default if nothing has already been returned.
	return result;
};

////////////////////////////////////////////////////////////////////////////////

It returns false as quickly as possible, but of course for a large object where the difference is deeply nested it could be less effective. In my own scenario, good handling of nested arrays is important.

Hope it helps someone needing this kind of 'wheel'.

Yeah, another answer...

Object.prototype.equals = function (object) {
    if (this.constructor !== object.constructor) return false;
    if (Object.keys(this).length !== Object.keys(object).length) return false;
    var obk;
    for (obk in object) {
        if (this[obk] !== object[obk])
            return false;
    }
    return true;
}

var aaa = JSON.parse('{"name":"mike","tel":"1324356584"}');
var bbb = JSON.parse('{"tel":"1324356584","name":"mike"}');
var ccc = JSON.parse('{"name":"mike","tel":"584"}');
var ddd = JSON.parse('{"name":"mike","tel":"1324356584", "work":"nope"}');

$("#ab").text(aaa.equals(bbb));
$("#ba").text(bbb.equals(aaa));
$("#bc").text(bbb.equals(ccc));
$("#ad").text(aaa.equals(ddd));

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
aaa equals bbb? <span id="ab"></span> <br/>
bbb equals aaa? <span id="ba"></span> <br/>
bbb equals ccc? <span id="bc"></span> <br/>
aaa equals ddd? <span id="ad"></span>

I have a much shorter function that will go deep into all sub objects or arrays. It is as efficient as JSON.stringify(obj1) === JSON.stringify(obj2) but JSON.stringify will not work if the order is not the same (as mentioned here).

var obj1 = { a : 1, b : 2 };
var obj2 = { b : 2, a : 1 };

console.log(JSON.stringify(obj1) === JSON.stringify(obj2)); // false

The function would also be a good start if you want to do something with the unequal values.

function arr_or_obj(v)
{ return !!v && (v.constructor === Object || v.constructor === Array); }

function deep_equal(v1, v2)
{
    if (arr_or_obj(v1) && arr_or_obj(v2) && v1.constructor === v2.constructor)
    {
        if (Object.keys(v1).length === Object.keys(v2).length) // check the length
        for (var i in v1)
        {
            if (!deep_equal(v1[i], v2[i]))
            { return false; }
        }
        else
        { return false; }
    }
    else if (v1 !== v2)
    { return false; }

    return true;
}

//////////////////////////////////////////////////////////////////
//////////////////////////////////////////////////////////////////

var obj1 = [
    {
        hat : {
            cap : ['something', null ],
            helmet : [ 'triple eight', 'pro-tec' ]
        },
        shoes : [ 'loafer', 'penny' ]
    },
    {
        beers : [ 'budweiser', 'busch' ],
        wines : [ 'barefoot', 'yellow tail' ]
    }
];

var obj2 = [
    {
        shoes : [ 'loafer', 'penny' ], // same even if the order is different
        hat : {
            cap : ['something', null ],
            helmet : [ 'triple eight', 'pro-tec' ]
        }
    },
    {
        beers : [ 'budweiser', 'busch' ],
        wines : [ 'barefoot', 'yellow tail' ]
    }
];

console.log(deep_equal(obj1, obj2)); // true
console.log(JSON.stringify(obj1) === JSON.stringify(obj2)); // false
console.log(deep_equal([], [])); // true
console.log(deep_equal({}, {})); // true
console.log(deep_equal([], {})); // false

And if you want to add support for Function, Date and RegExp, you can add this at the beginning of deep_equal (not tested):

if ((typeof obj1 === 'function' && typeof obj2 === 'function') ||
(obj1 instanceof Date && obj2 instanceof Date) ||
(obj1 instanceof RegExp && obj2 instanceof RegExp))
{
    obj1 = obj1.toString();
    obj2 = obj2.toString();
}

function isDeepEqual(obj1, obj2, testPrototypes = false) {
  if (obj1 === obj2) {
    return true
  }

  if (typeof obj1 === "function" && typeof obj2 === "function") {
    return obj1.toString() === obj2.toString()
  }

  if (obj1 instanceof Date && obj2 instanceof Date) {
    return obj1.getTime() === obj2.getTime()
  }

  if (
    Object.prototype.toString.call(obj1) !==
      Object.prototype.toString.call(obj2) ||
    typeof obj1 !== "object"
  ) {
    return false
  }

  const prototypesAreEqual = testPrototypes
    ? isDeepEqual(
        Object.getPrototypeOf(obj1),
        Object.getPrototypeOf(obj2),
        true
      )
    : true

  const obj1Props = Object.getOwnPropertyNames(obj1)
  const obj2Props = Object.getOwnPropertyNames(obj2)

  return (
    obj1Props.length === obj2Props.length &&
    prototypesAreEqual &&
    obj1Props.every(prop => isDeepEqual(obj1[prop], obj2[prop]))
  )
}

console.log(isDeepEqual({key: 'one'}, {key: 'first'}))
console.log(isDeepEqual({key: 'one'}, {key: 'one'}))

This is a classic javascript question! I created a method to check deep object equality with the feature of being able to select properties to ignore from comparison. Arguments are the two objects to compare, plus, an optional array of stringified property-to-ignore relative path.

function isObjectEqual( o1, o2, ignorePropsArr=[]) {
    // Deep Clone objects
    let _obj1 = JSON.parse(JSON.stringify(o1)),
        _obj2 = JSON.parse(JSON.stringify(o2));
    // Remove props to ignore
    ignorePropsArr.map( p => { 
        eval('_obj1.'+p+' = _obj2.'+p+' = "IGNORED"');
    });
    // compare as strings
    let s1 = JSON.stringify(_obj1),
        s2 = JSON.stringify(_obj2);
    // return [s1==s2,s1,s2];
    return s1==s2;
}

// Objects 0 and 1 are exact equals
obj0 = { price: 66544.10, RSIs: [0.000432334, 0.00046531], candles: {A: 543, B: 321, C: 4322}}
obj1 = { price: 66544.10, RSIs: [0.000432334, 0.00046531], candles: {A: 543, B: 321, C: 4322}}
obj2 = { price: 66544.12, RSIs: [0.000432334, 0.00046531], candles: {A: 543, B: 321, C: 4322}}
obj3 = { price: 66544.13, RSIs: [0.000432334, 0.00046531], candles: {A: 541, B: 321, C: 4322}}
obj4 = { price: 66544.14, RSIs: [0.000432334, 0.00046530], candles: {A: 543, B: 321, C: 4322}}

isObjectEqual(obj0,obj1) // true
isObjectEqual(obj0,obj2) // false
isObjectEqual(obj0,obj2,['price']) // true
isObjectEqual(obj0,obj3,['price']) // false
isObjectEqual(obj0,obj3,['price','candles.A']) // true
isObjectEqual(obj0,obj4,['price','RSIs[1]'])   // true

const one={name:'mohit' , age:30};
//const two ={name:'mohit',age:30};
const two ={age:30,name:'mohit'};

function isEquivalent(a, b) {
// Create arrays of property names
var aProps = Object.getOwnPropertyNames(a);
var bProps = Object.getOwnPropertyNames(b);



// If number of properties is different,
// objects are not equivalent
if (aProps.length != bProps.length) {
    return false;
}

for (var i = 0; i < aProps.length; i++) {
    var propName = aProps[i];

    // If values of same property are not equal,
    // objects are not equivalent
    if (a[propName] !== b[propName]) {
        return false;
    }
}

// If we made it this far, objects
// are considered equivalent
return true;
}

console.log(isEquivalent(one,two))

Though there are so many answers to this question already. My attempt is just to provide one more way of implementing this:

const primitveDataTypes = ['number', 'boolean', 'string', 'undefined'];
const isDateOrRegExp = (value) => value instanceof Date || value instanceof RegExp;
const compare = (first, second) => {
    let agg = true;
    if(typeof first === typeof second && primitveDataTypes.indexOf(typeof first) !== -1 && first !== second){
        agg =  false;
    }
    // adding support for Date and RegExp.
    else if(isDateOrRegExp(first) || isDateOrRegExp(second)){
        if(first.toString() !== second.toString()){
            agg = false;
        }
    }
    else {
        if(Array.isArray(first) && Array.isArray(second)){
        if(first.length === second.length){
             for(let i = 0; i < first.length; i++){
                if(typeof first[i] === 'object' && typeof second[i] === 'object'){
                    agg = compare(first[i], second[i]);
                }
                else if(first[i] !== second[i]){
                    agg = false;
                }
            }
        } else {
            agg = false;
        }
    } else {
        const firstKeys = Object.keys(first);
        const secondKeys = Object.keys(second);
        if(firstKeys.length !== secondKeys.length){
            agg = false;
        }
        for(let j = 0 ; j < firstKeys.length; j++){
            if(firstKeys[j] !== secondKeys[j]){
                agg = false;
            }
            if(first[firstKeys[j]] && second[secondKeys[j]] && typeof first[firstKeys[j]] === 'object' && typeof second[secondKeys[j]] === 'object'){
                agg = compare(first[firstKeys[j]], second[secondKeys[j]]);
             } 
             else if(first[firstKeys[j]] !== second[secondKeys[j]]){
                agg = false;
             } 
        }
    }
    }
    return agg;
}


console.log('result', compare({a: 1, b: { c: [4, {d:5}, {e:6}]}, r: null}, {a: 1, b: { c: [4, {d:5}, {e:6}]}, r: 'ffd'}));  //returns false.

I added an answer before but it was not perfect but this one will check equality for objects

function equalObjects(myObj1, myObj2){

let firstScore = 0;
let secondScore = 0;
let index=0;

let proprtiesArray = [];
let valuesArray = [];


let firstLength = 0;
let secondLength = 0;


for (const key in myObj1) {
    if (myObj1.hasOwnProperty(key)) {
        firstLength += 1;
        proprtiesArray.push(key);
        valuesArray.push(myObj1[key]);        
        firstScore +=1;
    }
}

for (const key in myObj2) {
    if (myObj2.hasOwnProperty(key)) {
        secondLength += 1;
        if (valuesArray[index] === myObj2[key] && proprtiesArray[index] === key) {
          secondScore +=1;
        }
        //console.log(myObj[key]);
        
        index += 1;
    }
    
}

if (secondScore == firstScore && firstLength === secondLength) {
   console.log("true", "equal objects");
   return true;
} else {
   console.log("false", "not equal objects");
   return false;
}

}

equalObjects({'firstName':'Ada','lastName':'Lovelace'},{'firstName':'Ada','lastName':'Lovelace'});

equalObjects({'firstName':'Ada','lastName':'Lovelace'},{'firstName':'Ada','lastName1':'Lovelace'});

equalObjects({'firstName':'Ada','lastName':'Lovelace'},{'firstName':'Ada','lastName':'Lovelace', 'missing': false});

function isEqual(obj1, obj2){
    type1 = typeof(obj1);
    type2 = typeof(obj2);
    if(type1===type2){
        switch (type1){
            case "object": return JSON.stringify(obj1)===JSON.stringify(obj2);
            case "function": return eval(obj1).toString()===eval(obj2).toString();
            default: return obj1==obj2;
        }
    }
    return false;
}//have not tried but should work.

Here is generic equality checker function that receives array of elements as input and compare them to each other. Works with all types of elements.

const isEqual = function(inputs = []) {
  // Checks an element if js object.
  const isObject = function(data) {
    return Object.prototype.toString.call(data) === '[object Object]';
  };
  // Sorts given object by its keys.
  const sortObjectByKey = function(obj) {
    const self = this;
    if (!obj) return {};
    return Object.keys(obj).sort().reduce((initialVal, item) => {
      initialVal[item] = !Array.isArray(obj[item]) &&
        typeof obj[item] === 'object'
        ? self.objectByKey(obj[item])
        : obj[item];
      return initialVal;
    }, {});
  };
  
  // Checks equality of all elements in the input against each other. Returns true | false
  return (
    inputs
      .map(
        input =>
          typeof input == 'undefined'
            ? ''
            : isObject(input)
                ? JSON.stringify(sortObjectByKey(input))
                : JSON.stringify(input)
      )
      .reduce(
        (prevValue, input) =>
          prevValue === '' || prevValue === input ? input : false,
        ''
      ) !== false
  );
};

// Tests (Made with Jest test framework.)
test('String equality check', () => {
  expect(isEqual(['murat'])).toEqual(true);
  expect(isEqual(['murat', 'john', 'doe'])).toEqual(false);
  expect(isEqual(['murat', 'murat', 'murat'])).toEqual(true);
});

test('Float equality check', () => {
  expect(isEqual([7.89, 3.45])).toEqual(false);
  expect(isEqual([7, 7.50])).toEqual(false);
  expect(isEqual([7.50, 7.50])).toEqual(true);
  expect(isEqual([7, 7])).toEqual(true);
  expect(isEqual([0.34, 0.33])).toEqual(false);
  expect(isEqual([0.33, 0.33])).toEqual(true);
});

test('Array equality check', () => {
  expect(isEqual([[1, 2, 3], [1, 2, 3]])).toEqual(true);
  expect(isEqual([[1, 3], [1, 2, 3]])).toEqual(false);
  expect(isEqual([['murat', 18], ['murat', 18]])).toEqual(true);
});

test('Object equality check', () => {
  let obj1 = {
    name: 'murat',
    age: 18
  };
  let obj2 = {
    name: 'murat',
    age: 18
  };
  let obj3 = {
    age: 18,
    name: 'murat'
  };
  let obj4 = {
    name: 'murat',
    age: 18,
    occupation: 'nothing'
  };
  expect(isEqual([obj1, obj2])).toEqual(true);
  expect(isEqual([obj1, obj2, obj3])).toEqual(true);
  expect(isEqual([obj1, obj2, obj3, obj4])).toEqual(false);
});

test('Weird equality checks', () => {
  expect(isEqual(['', {}])).toEqual(false);
  expect(isEqual([0, '0'])).toEqual(false);
});

There is also a gist

     let user1 = {
        name: "John",
        address: {
            line1: "55 Green Park Road",
            line2: {
              a:[1,2,3]
            } 
        },
        email:null
        }
    
     let user2 = {
        name: "John",
        address: {
            line1: "55 Green Park Road",
            line2: {
              a:[1,2,3]
            } 
        },
        email:null
         }
    
    // Method 1
    
    function isEqual(a, b) {
          return JSON.stringify(a) === JSON.stringify(b);
    }
    
    // Method 2
    
    function isEqual(a, b) {
      // checking type of a And b
      if(typeof a !== 'object' || typeof b !== 'object') {
        return false;
      }
      
      // Both are NULL
      if(!a && !b ) {
         return true;
      } else if(!a || !b) {
         return false;
      }
      
      let keysA = Object.keys(a);
      let keysB = Object.keys(b);
      if(keysA.length !== keysB.length) {
        return false;
      }
      for(let key in a) {
       if(!(key in b)) {
         return false;
       }
        
       if(typeof a[key] === 'object') {
         if(!isEqual(a[key], b[key]))
           {
             return false;
           }
       } else {
         if(a[key] !== b[key]) {
           return false;
         }
       }
      }
      
      return true;
    }



console.log(isEqual(user1,user2));

Here's a pretty clean CoffeeScript version of how you could do this:

Object::equals = (other) ->
  typeOf = Object::toString
  
  return false if typeOf.call(this) isnt typeOf.call(other)
  return `this == other` unless typeOf.call(other) is '[object Object]' or
                                typeOf.call(other) is '[object Array]'
  
  (return false unless this[key].equals other[key]) for key, value of this
  (return false if typeof this[key] is 'undefined') for key of other
  
  true

Here are the tests:

  describe "equals", ->
    
    it "should consider two numbers to be equal", ->
      assert 5.equals(5)
    
    it "should consider two empty objects to be equal", ->
      assert {}.equals({})
    
    it "should consider two objects with one key to be equal", ->
      assert {a: "banana"}.equals {a: "banana"}
    
    it "should consider two objects with keys in different orders to be equal", ->
      assert {a: "banana", kendall: "garrus"}.equals {kendall: "garrus", a: "banana"}
    
    it "should consider two objects with nested objects to be equal", ->
      assert {a: {fruit: "banana"}}.equals {a: {fruit: "banana"}}
    
    it "should consider two objects with nested objects that are jumbled to be equal", ->
      assert {a: {a: "banana", kendall: "garrus"}}.equals {a: {kendall: "garrus", a: "banana"}}
    
    it "should consider two objects with arrays as values to be equal", ->
      assert {a: ["apple", "banana"]}.equals {a: ["apple", "banana"]}
    
    
    
    it "should not consider an object to be equal to null", ->
      assert !({a: "banana"}.equals null)
    
    it "should not consider two objects with different keys to be equal", ->
      assert !({a: "banana"}.equals {})
      
    it "should not consider two objects with different values to be equal", ->
      assert !({a: "banana"}.equals {a: "grapefruit"})