jQuery object equality
EqualityJqueryEquality Problem Overview
How do I determine if two jQuery objects are equal? I would like to be able to search an array for a particular jQuery object.
$.inArray(jqobj, my_array);//-1
alert($("#deviceTypeRoot") == $("#deviceTypeRoot"));//False
alert($("#deviceTypeRoot") === $("#deviceTypeRoot"));//False
Equality Solutions
Solution 1 - Equality
Since jQuery 1.6, you can use .is. Below is the answer from over a year ago...
var a = $('#foo');
var b = a;
if (a.is(b)) {
// the same object!
}
If you want to see if two variables are actually the same object, eg:
var a = $('#foo');
var b = a;
...then you can check their unique IDs. Every time you create a new jQuery object it gets an id.
if ($.data(a) == $.data(b)) {
// the same object!
}
Though, the same could be achieved with a simple a === b, the above might at least show the next developer exactly what you're testing for.
In any case, that's probably not what you're after. If you wanted to check if two different jQuery objects contain the same set of elements, the you could use this:
$.fn.equals = function(compareTo) {
if (!compareTo || this.length != compareTo.length) {
return false;
}
for (var i = 0; i < this.length; ++i) {
if (this[i] !== compareTo[i]) {
return false;
}
}
return true;
};
var a = $('p');
var b = $('p');
if (a.equals(b)) {
// same set
}
Solution 2 - Equality
If you still don't know, you can get back the original object by:
alert($("#deviceTypeRoot")[0] == $("#deviceTypeRoot")[0]); //True
alert($("#deviceTypeRoot")[0] === $("#deviceTypeRoot")[0]);//True
because $("#deviceTypeRoot") also returns an array of objects which the selector has selected.
Solution 3 - Equality
The $.fn.equals(...) solution is probably the cleanest and most elegant one.
I have tried something quick and dirty like this:
JSON.stringify(a) == JSON.stringify(b)
It is probably expensive, but the comfortable thing is that it is implicitly recursive, while the elegant solution is not.
Just my 2 cents.
Solution 4 - Equality
It is, generally speaking, a bad idea to compare $(foo) with $(foo) as that is functionally equivalent to the following comparison:
<html>
<head>
<script language='javascript'>
function foo(bar) {
return ({ "object": bar });
}
$ = foo;
if ( $("a") == $("a") ) {
alert ("JS engine screw-up");
}
else {
alert ("Expected result");
}
</script>
</head>
</html>
Of course you would never expect "JS engine screw-up". I use "$" just to make it clear what jQuery is doing.
Whenever you call $("#foo") you are actually doing a jQuery("#foo") which returns a new object. So comparing them and expecting same object is not correct.
However what you CAN do may be is something like:
<html>
<head>
<script language='javascript'>
function foo(bar) {
return ({ "object": bar });
}
$ = foo;
if ( $("a").object == $("a").object ) {
alert ("Yep! Now it works");
}
else {
alert ("This should not happen");
}
</script>
</head>
</html>
So really you should perhaps compare the ID elements of the jQuery objects in your real program so something like
...
$(someIdSelector).attr("id") == $(someOtherIdSelector).attr("id")
is more appropriate.
Solution 5 - Equality
Use Underscore.js isEqual method http://underscorejs.org/#isEqual
Solution 6 - Equality
First order your object based on key using this function
function sortObject(o) {
return Object.keys(o).sort().reduce((r, k) => (r[k] = o[k], r), {});
}
Then, compare the stringified version of your object, using this funtion
function isEqualObject(a,b){
return JSON.stringify(sortObject(a)) == JSON.stringify(sortObject(b));
}
> Here is an example
Assuming objects keys are ordered differently and are of the same values
var obj1 = {"hello":"hi","world":"earth"}
var obj2 = {"world":"earth","hello":"hi"}
isEqualObject(obj1,obj2);//returns true
Solution 7 - Equality
If you want to check contents are equal or not then just use JSON.stringify(obj)
Eg - var a ={key:val};
var b ={key:val};
JSON.stringify(a) == JSON.stringify(b) -----> If contents are same you gets true.