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
Note that the contains method has been added to the String object in JavaScript 1.8.6, but that version is not currently standardized and is not in IE 11, Safari 7 or Opera 15. — D-Money, May 7 at 20:01
I assume it would have been impossible to use Google for finding sample code for such an extremely complex and abstract task. Heck, the code in the answer is almost 50 characters long! — user3477950, May 27 at 12:56

Derek 朕會功夫 · Accepted Answer · 2014-04-19 06:28:58Z

up vote 3310 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 Apr 19 at 6:28

Derek 朕會功夫
23.2k1456102

answered Nov 24 '09 at 13:05

Fabien Ménager
43.9k32140

363

@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

231

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

1083

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

14

@pramodc84 that link refers to the Array object indexOf method not to the String object method – gion_13 Apr 26 '12 at 13:26

40

Applied my new-found bitwise knowledge – Xeoncross Oct 10 '12 at 19:38

show 21 more comments

pixeline · Answer 2 · 2009-11-24 13:06:27Z

up vote 61 down vote

var index = haystack.indexOf(needle);

answered Nov 24 '09 at 13:06

pixeline
8,65334266

8

Nice use of variable names to make usage clear. – dbw Apr 27 at 1:40

add comment

rahul · Answer 3 · 2009-11-24 13:13:37Z

up vote 5 down vote

Use regular expression

RegExp.test(string)

answered Nov 24 '09 at 13:13

rahul
82.3k17132173

45

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

Benchmarks show otherwise; regex is more efficient in many cases, and more importantly, flexible enough to handle edge cases in a way that other solutions are not. – Chris Apr 10 at 21:48

2

Using regex usually results in 2 problems instead of one. – martynas Apr 15 at 8:48

add comment

Peter Mortensen · Answer 4 · 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++;
}

MillsJROSS · Answer 5 · 2009-11-24 15:52:20Z

up vote 13 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
72138

2

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

add comment

Peter Mortensen · Answer 6 · 2013-01-15 22:58:35Z

up vote 289 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
7,40785182

answered Dec 30 '09 at 4:23

Avi Flax
14.5k72245

79

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

28

@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

32

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

38

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

– Pavel Hodek Jun 7 '11 at 15:24

28

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

show 8 more comments

Peter Mortensen · Answer 7 · 2011-05-22 18:25:39Z

up vote 78 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
7,40785182

answered Mar 5 '10 at 9:53

Tardis
78953

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

12

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

1

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

Search can lead to bugs. As misaxi said, you then have to escape some characters. I was using search not realizing that the parameter expected a regex, and was searching for the pipe character. As it turns out, any string .search('|') == 0. – James Foster Mar 9 at 10:52

You can use an escapeRegExp function to make the serach text safe. function escapeRegExp(string){ return string.replace(/([.*+?^=!:${}()|\[\]\/\\])/g, "\\$1"); } from developer.mozilla.org/en/docs/Web/JavaScript/Guide/… – Mark Jun 5 at 16:23

add comment

aKzenT · Answer 8 · 2013-11-19 22:14:08Z

up vote 28 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
4,362637

answered Mar 14 '11 at 2:10

Chorinator
66979

8

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

5

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

4

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

1

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

add comment

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

up vote 14 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♦
21.9k155892

answered Oct 20 '11 at 21:50

writtinfool
16512

add comment

dplante · Answer 10 · 2012-05-30 07:31:32Z

up vote 24 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
1,73821123

answered May 29 '12 at 7:46

vaibhav
30639

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

add comment

zzzzBov · Answer 11 · 2012-09-13 03:45:50Z

up vote 18 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
60.6k1393155

6

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

6

@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

4

!!~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. – babinik 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

add comment

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

add comment

Peter Mortensen · Answer 13 · 2013-01-15 22:59:17Z

up vote 2 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
7,40785182

answered Nov 2 '12 at 12:24

Myxtic
713828

-1; this question is about strings, not arrays. – Mark Amery Apr 20 at 16:46

add comment

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

up vote 30 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
3,46421428

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

It is not support in chrome.....:( – Krunal Patel Jun 24 at 11:15

add comment

Tarun Gupta · Answer 15 · 2014-04-14 05:15:02Z

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.

-1; this question is about strings, not arrays. – Mark Amery Apr 20 at 16:49 — Mark Amery, Apr 20 at 16:49
a string is an array of chars :) – daslicht Apr 22 at 8:51 — daslicht, Apr 22 at 8:51

Ashish Aggarwal · Answer 16 · 2014-03-25 12:22:31Z

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.

Travis J · Answer 17 · 2014-04-21 14:15:09Z

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)
}

Thank you for EXPLAINING. You deserve the check. :3 – khaverim May 17 at 3:39 — khaverim, May 17 at 3:39

Aniket Kulkarni · Answer 18 · 2014-03-10 08:50:25Z

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 18 onwords.

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/

nachtigall · Answer 21 · 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

3 revs, 3 users 70% · Answer 22 · 2014-03-25 12:22:56Z

up vote 0 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 Mar 25 at 12:22

community wiki

3 revs, 3 users 70%
Satish Sharma

2

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 Feb 1 at 8:07

add comment

biziclop · Answer 23 · 2014-03-30 22:24:37Z

If you don't like the !!~, etc. tricks, you can simply add +1 to the result of .indexOf(). This way if a string is not found, -1 + 1 = 0 will be falsy, 0.. + 1 = 1.. will be truthy:

if( "StackOverflow".indexOf("Stack") + 1 )
     alert('contains');
else alert('does not contain');

2 revs, 2 users 67% · Answer 24 · 2014-05-02 20:26:01Z

Use the inbuilt and simplest one i.e match() on the string. To achieve what you are looking forward do this:

var stringData ="anyString Data";

var subStringToSearch = "any";

// This will give back the substring if matches and if not returns null
var doesContains = stringData.match(subStringToSearch);

if(doesContains !=null) {
    alert("Contains Substring");
}

Christian Landgren · Answer 25 · 2014-05-11 22:22:39Z

up vote 4 down vote

If you were looking for an alternative to write the ugly -1 check, you prepend a ~ tilde instead.

if (~haystack.indexOf('needle')) alert('found');

More details here

answered May 11 at 22:22

community wiki

Christian Landgren

2

This is brilliant. I don't understand how this doesn't have upvotes! – galdikas May 19 at 18:35

add comment

frieder · Answer 26 · 2014-05-27 12:52:06Z

The easyest way is indeed using indexOf.

To just check a string string for a substring substr you can use this method

string = "asdf";
substr = "as";
alert(string.indexOf(substr) == -1 ? false : true);

As you wanted the function string.contains(), you can implement it yourself like this:

String.prototype.contains = function(test) {
    return this.indexOf(test) == -1 ? false : true;
};

now you can use this ecen shorter method to check if a string contains a special substring:

string = "asdf";
alert(string.contains("as"));

Here is a JSFiddle as well.

asked	4 years ago
viewed	1455386 times
active	1 month ago

current community

your communities

more stack exchange communities

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

26 Answers

Syntax

Parameters

Example

Note

protected by Sean Vieira Nov 2 '12 at 12:31

Not the answer you're looking for? Browse other questions tagged javascript string or ask your own question.

Linked

Hot Network Questions

current community

your communities

more stack exchange communities

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

26 Answers

Syntax

Parameters

Example

Note

protected by Sean Vieira Nov 2 '12 at 12:31

Not the answer you're looking for? Browse other questions tagged javascript string or ask your own question.

Linked

Related

Hot Network Questions