How to match an empty dictionary in Javascript?
JavascriptDictionaryMatchJavascript Problem Overview
From the node REPL thing,
> d = {}
{}
> d === {}
false
> d == {}
false
Given I have an empty dictionary, how do I make sure it is an empty dictionary ?
Javascript Solutions
Solution 1 - Javascript
function isEmpty(obj) {
return Object.keys(obj).length === 0;
}
Solution 2 - Javascript
You could extend Object.prototype
with this isEmpty
method to check whether an object has no own properties:
Object.prototype.isEmpty = function() {
for (var prop in this) if (this.hasOwnProperty(prop)) return false;
return true;
};
Solution 3 - Javascript
How about using jQuery?
$.isEmptyObject(d)
Solution 4 - Javascript
Since it has no attributes, a for
loop won't have anything to iterate over. To give credit where it's due, I found this suggestion here.
function isEmpty(ob){
for(var i in ob){ return false;}
return true;
}
isEmpty({a:1}) // false
isEmpty({}) // true
Solution 5 - Javascript
This is what jQuery uses, works just fine. Though this does require the jQuery script to use isEmptyObject.
isEmptyObject: function( obj ) {
for ( var name in obj ) {
return false;
}
return true;
}
//Example
var temp = {};
$.isEmptyObject(temp); // returns True
temp ['a'] = 'some data';
$.isEmptyObject(temp); // returns False
If including jQuery is not an option, simply create a separate pure javascript function.
function isEmptyObject( obj ) {
for ( var name in obj ) {
return false;
}
return true;
}
//Example
var temp = {};
isEmptyObject(temp); // returns True
temp ['b'] = 'some data';
isEmptyObject(temp); // returns False
Solution 6 - Javascript
I'm far from a JavaScript scholar, but does the following work?
if (Object.getOwnPropertyNames(d).length == 0) {
// object is empty
}
It has the advantage of being a one line pure function call.
Solution 7 - Javascript
If performance isn't a consideration, this is a simple method that's easy to remember:
JSON.stringify(obj) === '{}'
Obviously you don't want to be stringifying large objects in a loop, though.
Solution 8 - Javascript
You'd have to check that it was of type 'object' like so:
(typeof(d) === 'object')
And then implement a short 'size' function to check it's empty, as mentioned here.
Solution 9 - Javascript
var SomeDictionary = {};
if(jQuery.isEmptyObject(SomeDictionary))
// Write some code for dictionary is empty condition
else
// Write some code for dictionary not empty condition
This Works fine.
Solution 10 - Javascript
If you try this on Node.js use this snippet, based on this code here
Object.defineProperty(Object.prototype, "isEmpty", {
enumerable: false,
value: function() {
for (var prop in this) if (this.hasOwnProperty(prop)) return false;
return true;
}
}
);