jQuery.inArray()

Categories: Utilities

jQuery.inArray( value, array ) Returns: Number

Description: Search for a specified value within an array and return its index (or -1 if not found).

version added: 1.2jQuery.inArray( value, array )

valueThe value to search for.

arrayAn array through which to search.

The $.inArray() method is similar to JavaScript's native .indexOf() method in that it returns -1 when it doesn't find a match. If the first element within the array matches value, $.inArray() returns 0.

Because JavaScript treats 0 as loosely equal to false (i.e. 0 == false, but 0 !== false), if we're checking for the presence of value within array, we need to check if it's not equal to (or greater than) -1.

Example:

Report the index of some elements in the array.

<!DOCTYPE html>
<html>
<head>
  <style>
  div { color:blue; }
  span { color:red; }
</style>
  <script src="http://code.jquery.com/jquery-latest.js"></script>
</head>
<body>
	
<div>"John" found at <span></span></div>
<div>4 found at <span></span></div>
<div>"Karl" not found, so <span></span></div>
<script>var arr = [ 4, "Pete", 8, "John" ];

$("span:eq(0)").text(jQuery.inArray("John", arr));
$("span:eq(1)").text(jQuery.inArray(4, arr));
$("span:eq(2)").text(jQuery.inArray("Karl", arr));

</script>
</body>
</html>

Demo:

Comments

Support requests, bug reports, and off-topic comments will be deleted without warning.
Please do post corrections or additional examples for jQuery.inArray() below. We aim to quickly move corrections into the documentation.
If you need help, post at the forums or in the #jquery IRC channel.
Report bugs on the bug tracker or the jQuery Forum.
Discussions about the API specifically should be addressed in the Developing jQuery Core forum.

Mean Mike

any chance of there being a case Insensitive option on this function ?

Neeraj Singh

I think this method should only return boolean value. period.

If user cares about the position then indexOf should be used.

I know this method has been there for a while and jQuery team is not going to change it. In that case it could be renamed to something like existsInArray and keep inArray as private function.

Znarkus

I think this function name is inappropriate, "inArray" somehow assumes a boolean return value. The documentation doesn't show the difference between this and indexOf(), why use this?

Karl Swedberg

Array.indexOf() is not supported in every browser. You would use this if you wanted to ensure cross-browser support. Here is the code from the source:

inArray: function( elem, array ) {
if ( array.indexOf ) {
return array.indexOf( elem );
}

for ( var i = 0, length = array.length; i < length; i++ ) {
if ( array[ i ] === elem ) {
return i;
}
}

return -1;
}

Znarkus

Then I think the first paragraph should be rephrased, and the function name changed to indexOf (as that is what it does) :)

It would be cool if jQuery had an inArray()

inArray: function( elem, array ) {
return $.indexOf(elem, array) !== -1;
}

Karl Swedberg

Looks like the short description was nested incorrectly in the XML. Now that it's up there, does that clear things up a bit?

As for changing the function name, it's very unlikely that that would happen with a function that's been in the API for a couple years. But if you feel strongly about it, feel free to report it on the jQuery forum.

Znarkus

Yeah, much better thanks! Maybe something about it wrapping the native indexOf when there's support, for optimization junkies. Thanks for clearing this up!

Edit: Started a discussion in the forum http://forum.jquery.com/#Topic/14737000000668064

Bharat

What is the performance impact if I use this to find out if the objects in one array is contained in other bigger array. Is there any other faster way to do this?
Thanks,
Bharat

jQuery API