How can I check if one string contains another substring in JavaScript?

Question

Usually I would expect a String.contains() method, but there doesn't seem to be one.

@Michel Not a dupe. That question is about arrays. This one is about strings. — Mark Amery, Jan 7 at 19:05

Greg · Accepted Answer · 2013-12-11 16:32:20Z

up vote 2747 down vote accepted

indexOf returns the position of the string in the other string. If not found, it will return -1:

var s = "foo";
alert(s.indexOf("oo") != -1);

edited Dec 11 '13 at 16:32

Greg
4,078929

answered Nov 24 '09 at 13:05

Fabien Ménager
37.6k32038

113

you should be using !== fyi. – Steve May 26 '11 at 19:29

139

> would save a byte :) – Steve Jun 6 '11 at 22:39

296

@Steve indexOf always returns a number so there’s no need to use !==. If you want to save bytes, you could use ~'foo'.indexOf('oo') which returns a truthy value if the substring is found, and a falsy value (0) if it isn’t. – Mathias Bynens Jul 7 '11 at 11:00

187

For the curious: in two's compliment systems, -1 is represented in binary as all 1s (1111 1111 1111 1111 1111 1111 1111 1111 for 32 bit). The bitwise inverse (~) of this is all zeros, or just zero, and therefore falsy. That's why the squiggle trick works, and it is pretty bad-ass if I must say so myself. – Adam Tolley Sep 14 '11 at 21:36

847

Writing code that is unreadable because it's full of tricks isn't "bad ass" so much as just "bad". – boxed Dec 23 '11 at 8:45

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Peter Mortensen · Answer 2 · 2013-01-15 22:58:35Z

up vote 249 down vote

You can easily add a contains method to String with this statement:

String.prototype.contains = function(it) { return this.indexOf(it) != -1; };

Note: see the comments below for a valid argument for not using this. My advice: use your own judgement.

edited Jan 15 '13 at 22:58

Peter Mortensen
6,84984677

answered Dec 30 '09 at 4:23

Avi Flax
12.5k62041

65

Don't modify objects you don't own. nczonline.net/blog/2010/03/02/… – zachleat Feb 17 '11 at 19:59

24

@zachleat, that understandable in practice. But "foobar".contains("bar") would be a really useful exception to the rule. – nathan.f77 Feb 22 '11 at 9:50

27

Eh, my preference would be to adapt my mental model to fit JavaScript and just use indexOf. It will make the code easier to understand for the next JavaScripter that comes along and has to read it. – zachleat Mar 4 '11 at 16:03

33

if (typeof String.prototype.contains === 'undefined') {
  String.prototype.contains = function(it) { return this.indexOf(it) != -1; };
}

– Pavel Hodek Jun 7 '11 at 15:24

23

I this it is preferrable to use this function if you are going to be using this kind of indexOf's frequently. @zachleat, I would disagree that using indexOf is more readable than contains. Contains describes what is happening, where to some indexOf() != -1 may not be so transparent. But to each their own, as long as you're consistant. – smdrager Jul 11 '11 at 14:03

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Peter Mortensen · Answer 3 · 2012-10-18 19:24:03Z

The problem with your code is that JavaScript is case sensitive. Your method call

indexof()

should actually be

indexOf()

Try fixing it and see if that helps:

if (test.indexOf("title") !=-1) {
    alert(elm);
    foundLinks++;
}

Peter Mortensen · Answer 4 · 2011-05-22 18:25:39Z

up vote 62 down vote

You could use the JavaScript search() method.

Syntax is: string.search(regexp)

It returns the position of the match, or -1 if no match is found.

See examples there: jsref_search

You don't need a complicated regular expression syntax. If you are not familiar with them a simple st.search("title") will do. If you want your test to be case insensitive, then you should do st.search(/title/i).

edited May 22 '11 at 18:25

Peter Mortensen
6,84984677

answered Mar 5 '10 at 9:53

Tardis
62953

5

This seems like it would be slower than the indexOf function because it would have to parse the RegEx. However, if you want something case insensitive, your way would be the way to go (I think), although that was not what was asked. Even though it wasn't asked, I'm voting this up just because of the case insensitive option. – PiPeep Jun 3 '10 at 22:21

10

I haven't run a benchmark, but would str.toLowerCase().indexOf(searchstr.toLowerCase()) be much more efficient for case-insensitive search? – Tim S. Jan 31 '12 at 10:29

With a benchmark and it turns out search is more efficient for case insensitive searching. jsperf.com/string-compare-perf-test But it could be tricky to use regex search as you need to escape some characters. – misaxi Jul 9 '13 at 6:13

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pixeline · Answer 5 · 2009-11-24 13:06:27Z

up vote 48 down vote

var index = haystack.indexOf(needle);

answered Nov 24 '09 at 13:06

pixeline
7,88033960

add comment

aKzenT · Answer 6 · 2013-11-19 22:14:08Z

up vote 29 down vote

You can use jQuery's :contains selector.

$("div:contains('John')")

Check it here: http://api.jquery.com/contains-selector/

edited Nov 19 '13 at 22:14

aKzenT
4,090536

answered Mar 14 '11 at 2:10

Chorinator
61069

5

That searches DOM elements though… – sam Sep 26 '13 at 21:03

2

dom parsing has nothing to do with the question – oligofren Nov 1 '13 at 12:06

2

yeah, how did this get 31 up votes? it has nothing to do with the question asked .... it's cool and interesting and something I didn't know, but is quite unrelated – Landon Nov 13 '13 at 0:13

it's loosely related... if the string you're searching through happens to be located within a DOM element, jQuery's :contains selector can be used. – Joshua Burns Nov 20 '13 at 20:50

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dplante · Answer 7 · 2012-05-30 07:31:32Z

up vote 22 down vote

This piece of code should work well:

var str="This is testing for javascript search !!!";
if(str.search("for") != -1) {
   //logic
}

edited May 30 '12 at 7:31

dplante
1,71621022

answered May 29 '12 at 7:46

vaibhav
26829

can you explain a bit more extensively your answer? tnx – Daniele B May 29 '12 at 23:27

it searches for the passed character or a word if it is found then search returns a integer value which is the position of word in the entire string. If a word or a character is not found then it search function returns -1. – vaibhav Jun 1 '12 at 4:43

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eliocs · Answer 8 · 2013-02-06 09:53:14Z

up vote 20 down vote

A contains method has been added to Strings in Javascript 1.8.6:

"potato".contains("to");
> true

Of course, we will have to wait decades for mainstream support :P

(source)

edited Feb 6 '13 at 9:53

answered Jan 7 '13 at 10:23

eliocs
2,72221326

1

because I was used to "contains" in other languages and just implemented my feature with it, I just ran into the error. So, short feedback about the support. Firefox 19 - OSX => OK, Firefox 19 - Windows => NOK, Chrome - OSX,Windows => NOK – phammer Feb 21 '13 at 10:18

1

Like this? String.prototype.contains = function (segment) { return this.indexOf(segment) !== -1; }; (BTW: Doing things on the prototype is bad) – Nijikokun May 10 '13 at 2:50

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animuson · Answer 9 · 2011-11-20 01:35:31Z

up vote 15 down vote

This just worked for me. It selects for strings that do not contain the term "Deleted:"

if (eventString.indexOf("Deleted:") == -1)

edited Nov 20 '11 at 1:35

animuson♦
19.5k145484

answered Oct 20 '11 at 21:50

writtinfool
16712

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zzzzBov · Answer 10 · 2012-09-13 03:45:50Z

up vote 15 down vote

A common way to write a contains method in JS is:

if (!String.prototype.contains) {
    String.prototype.contains = function (arg) {
        return !!~this.indexOf(arg);
    };
}

The bitwise negation operator (~) is used to turn -1 into 0 (falsey), and all other values will be non-zero (truthy).

The double boolean negation operators are used to cast the number into a boolean.

answered Sep 13 '12 at 3:45

zzzzBov
52.9k773132

5

What's the advantage of !!~ over >-1? – alex Dec 12 '12 at 4:29

@alex, There isn't any particular advantage other than not relying on magic numbers. Use what you feel comfortable with. – zzzzBov Dec 12 '12 at 4:59

5

@zzzzBov !~~ is just as much relying on the magic number -1, and the fact that its bitwise representation is the complement of 0. – Martijn May 14 '13 at 9:33

2

!!~this.indexOf(arg); isn't easy understandable and not as clear in the context as it must be. It also relays on the fact ~-1 is 0, agreed with @Martijn. Also it's slower than simple comparison with -1. But clearness is the main factor. – Nick May 20 '13 at 15:40

1

@Nick, I never claimed that it was a good way, I just said it was a common way. As far as clarity is concerned, I feel that it's a reasonable way to save a couple bytes for a library, but I tend to use foo.indexOf('bar') > -1 – zzzzBov May 20 '13 at 15:43

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MillsJROSS · Answer 11 · 2009-11-24 15:52:20Z

up vote 14 down vote

You need to call indexOf with a capital "O" as mentioned. It should also be noted, that in JavaScript class is a reserved word, you need to use className to get this data attribute. The reason it's probably failing is because it's returning a null value. You can do the following to get your class value...

var test = elm.getAttribute("className");
//or
var test = elm.className

answered Nov 24 '09 at 15:52

MillsJROSS
70338

2

Your first approach is not correct: elm.getAttribute("class") == elm.className != elm.getAttribute("className") – SebastianG Mar 12 '13 at 14:22

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2 revs, 2 users 80% · Answer 12 · 2012-10-18 19:25:10Z

up vote 12 down vote

Another option of doing this is:

You can use the match function, that is, something like:

x = "teststring";

if (x.match("test")) {
     // Code
}

edited Oct 18 '12 at 19:25

community wiki

2 revs, 2 users 80%
PrivateSniper

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Travis J · Answer 13 · 2013-12-05 21:20:04Z

~~_{jsFiddle Demo}~~

_{Your code works, however you have misspelled the API function. As a result of the misspelling, you were getting the error "Uncaught TypeError: Object title has no method 'indexof'" which was preventing the execution of the rest of your script.}

~~_{Many functions in javascript use the "camel case" naming convention. This dictates that the first letter be lower case, and the first letter of every other word be capitalized. Thus, by convention,}~~you were looking for .indexOf^MDN.

indexOf is going to return an index to the matched substring. The index will correlate to where the substring starts. If there is no match, a -1 is returned. Here is a simple demo of that concept:

var str = "Hello World";// For example, lets search this string,
var term = "World";// for the term "World",
var index = str.indexOf(term);// and get its index.
if(index != -1){// If the index is not -1 then the term was matched in the string,
 alert(index);// and we can do some work based on that logic. (6 is alerted)
}

_{striked out content was in response to a later edit to the question related meta post}

rahul · Answer 14 · 2009-11-24 13:13:37Z

up vote 3 down vote

Use regular expression

RegExp.test(string)

answered Nov 24 '09 at 13:13

rahul
75.3k16115167

40

Using a regex is a little overhead to only check for the presence of a substring. – Fabian Vilers Nov 24 '09 at 13:55

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Peter Mortensen · Answer 15 · 2013-01-15 22:59:17Z

up vote 3 down vote

indexOf didn't work for me in Internet Explorer 8, and so I used jQuery's inArray() method:

$.inArray("search_string", in_array)

edited Jan 15 '13 at 22:59

Peter Mortensen
6,84984677

answered Nov 2 '12 at 12:24

Myxtic
403320

add comment

Tarun · Answer 16 · 2013-02-28 07:50:18Z

JavaScript code to use contain method in an array

 <html>
<head>
<h2>Use of contains() method</h2>
<script>
Array.prototype.contains = function (element) {
for (var i = 0; i < this.length; i++) {
if (this[i] == element) {
return true;
}
}
return false;
}
arr1 = ["Rose", "India", "Technologies"];
document.write("The condition is "+arr1.contains("India")+"<br>");
</script>
</head>
<b>[If the specified element is present in the array, it returns true otherwise 
returns false.]</b>
</html>

In the given code the contain method determines whether the specified element is present in the array or not. If the specified element is present in the array, it returns true otherwise it returns false.

Tjaart · Answer 17 · 2013-08-22 11:40:35Z

Since there is a complaint about using the prototype, and since using indexOf makes your code less readable, and since regexp is overkill:

function stringContains(inputString, stringToFind) 
{
    return (inputString.indexOf(stringToFind) != -1);
}

That is the compromise I ended up going for.

hjpotter92 · Answer 18 · 2013-10-22 10:18:45Z

String.contains() introduced in JavaScript 1.8.6

Determines whether one string may be found within another string, returning true or false as appropriate.

Syntax

var contained = str.contains(searchString [, position]);

Parameters

searchString

A string to be searched for within this string.

position

The position in this string at which to begin searching for searchString defaults to 0.

Example

var str = "To be, or not to be, that is the question.";

console.log(str.contains("To be"));    // true
console.log(str.contains("question")); // true
console.log(str.contains("To be", 1)); // false

Note

Only supported in Firefox from version 19.

Jay Harris · Answer 19 · 2014-01-13 14:09:41Z

Since the question is pretty popular, I thought I could add a little modern flavor to the code.

var allLinks = content.document.getElementsByTagName("a")
,   il       = allLinks.length
,   i        = 0
,   test
,   alrt;

while (i < il) {
  elm  = allLinks[i++];
  test = elm.getAttribute("class");

  if (test.indexOf("title") > -1) console.log(elm), foundLinks++;   
}
alrt = foundLinks ? "Found " + foundLinks + " title class" : "No title class found";
console.log(alrt);

Btw the correct answer is misspelling indexOf or the non-standard String.contains. Loading an external library (especially if the code is written in pure javascript) or messing with String.prototype or using a regex is a little over kill.

Oliver · Answer 20 · 2013-11-28 20:56:45Z

Try this:

if ('Hello, World!'.indexOf('orl') !== -1)
    alert("The string 'Hello World' contains the substring 'orl'!");
else
    alert("The string 'Hello World' does not contain the substring 'orl'!");

Here is an example: http://jsfiddle.net/oliverni/cb8xw/

2 revs, 2 users 74% · Answer 21 · 2014-01-07 13:05:32Z

up vote 1 down vote

this is function to check a substring is exists in a string or not

function isStringMatch(str, str_to_match)
{
   return (str.indexOf(str_to_match) > 0);
}

edited Jan 7 at 13:05

community wiki

2 revs, 2 users 74%
Satish Sharma

Just a heads up... this should be either >=0, >-1, or (my preference) !== -1, as this will fail in its current form if the string begins with the substring. – Karl White yesterday

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nachtigall · Answer 22 · 2013-12-13 20:05:22Z

Instead of using code snippets found here and there on the web, you can also use a well-tested and documented library like Underscore.string for this. It has an include method that does what you want:

_.str.include("foobar", "ob")
=> true

Here is the description of the library, it just adds 9kb but gives you all the advantages a well-tested and documented library has over copy'n'paste code snippets:

Underscore.string is JavaScript library for comfortable manipulation with strings, extension for Underscore.js inspired by Prototype.js, Right.js, Underscore and beautiful Ruby language.

Underscore.string provides you several useful functions: capitalize, clean, includes, count, escapeHTML, unescapeHTML, insert, splice, startsWith, endsWith, titleize, trim, truncate and so on.

Note well, Underscore.string is influenced by Underscore.js but can be used without it.

I don't see how figuring out the underscore method is in any way superior to simply using the well-documented core functionality provided in javascript, as illustrated here. To the type of coder that copies and pastes code, your sample code would be no more or less a "copy'n'paste code snippet" than any other solution provided here, except, it would require the addition of a library. Adding libraries simply to accomplish tasks that are just as easily done using the native language, regardless of library size, is bad advice. -1 from me for knee-jerk library use on a old question. — Chris, Jan 12 at 5:37

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How can I check if one string contains another substring in JavaScript?

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