Javascript, Fastest way to know if a certain value is in a array?

Question

Possible Duplicate:
array.contains(obj) in JavaScript

Let's say I have an array = [0,8,5]

What is the fastest way to know if 8 is inside this one.. for example:

if(array.contain(8)){
 // return true
}

I found this : Fastest way to check if a value exist in a list (Python)

and this : fastest way to detect if a value is in a set of values in Javascript

But this don't answer to my question. Thank you.

http://stackoverflow.com/questions/237104/array-containsobj-in-javascript — zbrunson, Nov 27 '12 at 15:49

Muthu Kumaran · Accepted Answer · 2012-11-27T15:58:04.773

10

Use indexOf() to check whether value is exist or not

array.indexOf(8)

Sample Code,

var arr = [0,8,5];
alert(arr.indexOf(8)); //returns key

Update

For IE support

//IE support
if (!Array.prototype.indexOf) { 
    Array.prototype.indexOf = function(obj, start) {
         for (var i = (start || 0), j = this.length; i < j; i++) {
             if (this[i] === obj) { return i; }
         }
         return -1;
    }
}

var arr = [0,8,5];
alert(arr.indexOf(8))

edited Nov 27 '12 at 15:58

answered Nov 27 '12 at 15:49

Muthu Kumaran

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This of course assumes you're not using an old browser. – Niet the Dark Absol Nov 27 '12 at 15:50
1

`Array.indexOf` doesn't work in IE < 9. – gen_Eric Nov 27 '12 at 15:50
@RocketHazmat I checked on IE 8, it's working for me. http://jsfiddle.net/muthkum/LhvwV/1/ – Muthu Kumaran Nov 27 '12 at 15:52
1

@MuthuKumaran: no way. https://developer.mozilla.org/en-US/docs/JavaScript/Reference/Global_Objects/Array/indexOf – naveen Nov 27 '12 at 15:55
1

@MuthuKumaran: That's because that fiddle is using MooTools. MooTools adds `Array.prototype.indexOf` if it doesn't exist. – gen_Eric Nov 27 '12 at 15:55
oh that explains why it worked on IE. – Muthu Kumaran Nov 27 '12 at 15:56
Thanks to all for pointing it out. I updated my answer. – Muthu Kumaran Nov 27 '12 at 15:58
1

+1: MDC also recommends a more elaborate implementation though https://developer.mozilla.org/en-US/docs/JavaScript/Reference/Global_Objects/Array/IndexOf#Compatibility – naveen Nov 27 '12 at 16:03
You should mention that if the item isn't in the array, `.indexOf()` returns -1 – Mark Kramer Nov 05 '17 at 00:05
`.includes()` is actually faster than `.indexOf()` – Leeland Miller May 03 '18 at 00:54

score 4 · Answer 2 · answered Nov 27 '12 at 15:51

4

You can use a indexOf() function

var fruits = ["a1", "a2", "a3", "a4"];
var a = fruits.indexOf("a3");

The output will be: 2

answered Nov 27 '12 at 15:51

Dineshkani

2,899
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2

`Array.indexOf` doesn't work in IE < 9. – gen_Eric Nov 27 '12 at 15:51
1

Refer this answer for ie < 9 browser http://stackoverflow.com/questions/1744310/how-to-fix-array-indexof-in-javascript-for-ie-browsers – Dineshkani Nov 27 '12 at 15:54

Rahul Tripathi · Answer 3 · 2012-11-27T15:59:25.910

0

You can use indexOf or you can try this:

$.inArray(value, array)

edited Nov 27 '12 at 15:59

answered Nov 27 '12 at 15:50

Rahul Tripathi

168,305
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score -1 · Answer 4 · edited Nov 27 '12 at 16:04

-1

phpjs has a nice php's in_array function's port to javascript, you may use it

http://phpjs.org/functions/in_array/

see example:

in_array('van', ['Kevin', 'van', 'Zonneveld']);

edited Nov 27 '12 at 16:04

gen_Eric

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answered Nov 27 '12 at 15:54

Kemal Dağ

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Javascript, Fastest way to know if a certain value is in a array?

4 Answers4

Update