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The Object.is() method determines whether two values are the same value, this is the correct answer and this is how you fish with your bare hands :D.
Approach 1: Use is() method to check both selected elements are same or not. It takes an element as argument and check if it is equal to the other element.
eq() returns it as a jQuery object, meaning the DOM element is wrapped in the jQuery wrapper, which means that it accepts jQuery functions. . get() returns an array of raw DOM elements. You may manipulate each of them by accessing its attributes and invoking its functions as you would on a raw DOM element.
$() = window. jQuery() $()/jQuery() is a selector function that selects DOM elements. Most of the time you will need to start with $() function. It is advisable to use jQuery after DOM is loaded fully.
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;
};
Source
var a = $('p');
var b = $('p');
if (a.equals(b)) {
// same set
}
If you still don't know, you can get back the original object by:
alert($("#deviceTypeRoot")[0] == $("#deviceTypeRoot")[0]); //True
alert($("#deviceTypeRoot")[0] === $("#deviceTypeRoot")[0]);//True
because $("#deviceTypeRoot") also returns an array of objects which the selector has selected.
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.
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.
Use Underscore.js isEqual method http://underscorejs.org/#isEqual
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