How to check if a value exists in an object using JavaScript
JavascriptJavascript Problem Overview
I have an object in JavaScript:
var obj = {
"a": "test1",
"b": "test2"
}
How do I check that test1 exists in the object as a value?
Javascript Solutions
Solution 1 - Javascript
You can turn the values of an Object into an array and test that a string is present. It assumes that the Object is not nested and the string is an exact match:
var obj = { a: 'test1', b: 'test2' };
if (Object.values(obj).indexOf('test1') > -1) {
console.log('has test1');
}
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/values
Solution 2 - Javascript
You can use the Array method .some
:
var exists = Object.keys(obj).some(function(k) {
return obj[k] === "test1";
});
Solution 3 - Javascript
Shortest ES6+ one liner:
let exists = Object.values(obj).includes("test1");
Solution 4 - Javascript
Try:
var obj = {
"a": "test1",
"b": "test2"
};
Object.keys(obj).forEach(function(key) {
if (obj[key] == 'test1') {
alert('exists');
}
});
Or
var obj = {
"a": "test1",
"b": "test2"
};
var found = Object.keys(obj).filter(function(key) {
return obj[key] === 'test1';
});
if (found.length) {
alert('exists');
}
This will not work for NaN
and -0
for those values. You can use (instead of ===
) what is new in ECMAScript 6:
Object.is(obj[key], value);
With modern browsers you can also use:
var obj = {
"a": "test1",
"b": "test2"
};
if (Object.values(obj).includes('test1')) {
alert('exists');
}
Solution 5 - Javascript
Use a for...in
loop:
for (let k in obj) {
if (obj[k] === "test1") {
return true;
}
}
Solution 6 - Javascript
You can use Object.values():
> The Object.values()
method returns an array of a given object's own
> enumerable property values, in the same order as that provided by a
> for...in
loop (the difference being that a for-in loop enumerates
> properties in the prototype chain as well).
and then use the indexOf() method:
> The indexOf()
method returns the first index at which a given
> element can be found in the array, or -1 if it is not present.
For example:
Object.values(obj).indexOf("test`") >= 0
A more verbose example is below:
var obj = {
"a": "test1",
"b": "test2"
}
console.log(Object.values(obj).indexOf("test1")); // 0
console.log(Object.values(obj).indexOf("test2")); // 1
console.log(Object.values(obj).indexOf("test1") >= 0); // true
console.log(Object.values(obj).indexOf("test2") >= 0); // true
console.log(Object.values(obj).indexOf("test10")); // -1
console.log(Object.values(obj).indexOf("test10") >= 0); // false
Solution 7 - Javascript
For a one-liner, I would say:
exist = Object.values(obj).includes("test1");
console.log(exist);
Solution 8 - Javascript
I did a test with all these examples, and I ran this in Node.js v8.11.2. Take this as a guide to select your best choice.
let i, tt;
const obj = { a: 'test1', b: 'test2', c: 'test3', d: 'test4', e: 'test5', f: 'test6' };
console.time("test1")
i = 0;
for( ; i<1000000; i=i+1) {
if (Object.values(obj).indexOf('test4') > -1) {
tt = true;
}
}
console.timeEnd("test1")
console.time("test1.1")
i = 0;
for( ; i<1000000 ; i=i+1) {
if (~Object.values(obj).indexOf('test4')) {
tt = true;
}
}
console.timeEnd("test1.1")
console.time("test2")
i = 0;
for( ; i<1000000; i=i+1) {
if (Object.values(obj).includes('test4')) {
tt = true;
}
}
console.timeEnd("test2")
console.time("test3")
i = 0;
for( ; i<1000000 ; i=i+1) {
for(const item in obj) {
if(obj[item] == 'test4') {
tt = true;
break;
}
}
}
console.timeEnd("test3")
console.time("test3.1")
i = 0;
for( ; i<1000000; i=i+1) {
for(const [item, value] in obj) {
if(value == 'test4') {
tt = true;
break;
}
}
}
console.timeEnd("test3.1")
console.time("test4")
i = 0;
for( ; i<1000000; i=i+1) {
tt = Object.values(obj).some((val, val2) => {
return val == "test4"
});
}
console.timeEnd("test4")
console.time("test5")
i = 0;
for( ; i<1000000; i=i+1) {
const arr = Object.keys(obj);
const len = arr.length;
let i2 = 0;
for( ; i2<len ; i2=i2+1) {
if(obj[arr[i2]] == "test4") {
tt = true;
break;
}
}
}
console.timeEnd("test5")
Output on my server
test1: 272.325 ms
test1.1: 246.316 ms
test2: 251.98 0ms
test3: 73.284 ms
test3.1: 102.029 ms
test4: 339.299 ms
test5: 85.527 ms
Solution 9 - Javascript
if (Object.values(obj).includes('test1')){
return true
}
Solution 10 - Javascript
you can try this one
var obj = {
"a": "test1",
"b": "test2"
};
const findSpecificStr = (obj, str) => {
return Object.values(obj).includes(str);
}
findSpecificStr(obj, 'test1');
Solution 11 - Javascript
You can try this:
function checkIfExistingValue(obj, key, value) {
return obj.hasOwnProperty(key) && obj[key] === value;
}
var test = [{name : "jack", sex: F}, {name: "joe", sex: M}]
console.log(test.some(function(person) { return checkIfExistingValue(person, "name", "jack"); }));
Solution 12 - Javascript
In new version if ecma script now we can check vslues by ?.
operations..
Its so simpler and easy yo check values in a object or nested or objects
var obj = {
"a": "test1",
"b": "test2"
}
if(obj?.a) return "i got the value"
Similarly since in Javascript most used primitive type is Object
We can use this arrays, functions etc too
aFunc = () => { return "gotcha"; }
aFunc?.() // returns gotcha
myArray = [1,2,3]
myArray?.[3] // returns undefined
Thanks
Solution 13 - Javascript
Best way to find value exists in an Object using Object.keys()
obj = {
"India" : {
"Karnataka" : ["Bangalore", "Mysore"],
"Maharashtra" : ["Mumbai", "Pune"]
},
"USA" : {
"Texas" : ["Dallas", "Houston"],
"IL" : ["Chicago", "Aurora", "Pune"]
}
}
function nameCity(e){
var finalAns = []
var ans = [];
ans = Object.keys(e).forEach((a)=>{
for(var c in e[a]){
e[a][c].forEach(v=>{
if(v === "Pune"){
finalAns.push(c)
}
})
}
})
console.log(finalAns)
}
nameCity(obj)
Solution 14 - Javascript
var obj = {"a": "test1", "b": "test2"};
var getValuesOfObject = Object.values(obj)
for(index = 0; index < getValuesOfObject.length; index++){
return Boolean(getValuesOfObject[index] === "test1")
}
The Object.values() method returned an array (assigned to getValuesOfObject) containing the given object's (obj) own enumerable property values. The array was iterated using the for
loop to retrieve each value (values in the getValuesfromObject) and returns a Boolean() function to find out if the expression ("text1" is a value in the looping array) is true.
Solution 15 - Javascript
getValue = function (object, key) {
return key.split(".").reduce(function (obj, val) {
return (typeof obj == "undefined" || obj === null || obj === "") ? obj : (_.isString(obj[val]) ? obj[val].trim() : obj[val]);}, object);
};
var obj = {
"a": "test1",
"b": "test2"
};
Function called:
getValue(obj, "a");
Solution 16 - Javascript
_.has()
method is used to check whether the path is a direct property of the object or not. It returns true if the path exists, else it returns false.
> var object = { 'a': { 'b': 2 } }; > console.log(.has(object, 'a.b')); > console.log(.has(object, ['a','b'])); > console.log(_.has(object, ['a','b','c']));
Output: true true false
Solution 17 - Javascript
if( myObj.hasOwnProperty('key') && myObj['key'] === value ){
...
}
Solution 18 - Javascript
The simple answer to this is given below.
This is working because every JavaScript type has a “constructor” property on it prototype”.
let array = [] array.constructor === Array // => true
let data = {}
data.constructor === Object
// => true
Solution 19 - Javascript
This should be a simple check.
Example 1
var myObj = {"a": "test1"}
if(myObj.a == "test1") {
alert("test1 exists!");
}