How to replace all occurrences of a string in JavaScript?

+2821 votes
asked Jul 17, 2009 by click-upvote

I have this string:

"Test abc test test abc test test test abc test test abc"

Doing

str = str.replace('abc', '');

seems to only remove the first occurrence of abc in the string above. How can I replace all occurrences of it?

28 Answers

+460 votes
answered May 6, 2009 by adam-a

Using a regular expression with the g flag set will replace all:

someString = 'the cat looks like a cat';
anotherString = someString.replace(/cat/g, 'dog');
// anotherString now contains "the dog looks like a dog"

See here also

+43 votes
answered May 6, 2009 by scronide

Match against a global regular expression:

anotherString = someString.replace(/cat/g, 'dog');
+3352 votes
answered Jul 17, 2009 by sean-bright
str = str.replace(/abc/g, '');

In response to comment:

var find = 'abc';
var re = new RegExp(find, 'g');

str = str.replace(re, '');

In response to Click Upvote's comment, you could simplify it even more:

function replaceAll(str, find, replace) {
    return str.replace(new RegExp(find, 'g'), replace);
}

Note: Regular expressions contain special (meta) characters, and as such it is dangerous to blindly pass an argument in the find function above without pre-processing it to escape those characters. This is covered in the Mozilla Developer Network's JavaScript Guide on Regular Expressions, where they present the following utility function:

function escapeRegExp(str) {
    return str.replace(/([.*+?^=!:${}()|\[\]\/\\])/g, "\\$1");
}

So in order to make the replaceAll() function above safer, it could be modified to the following if you also include escapeRegExp:

function replaceAll(str, find, replace) {
    return str.replace(new RegExp(escapeRegExp(find), 'g'), replace);
}
+31 votes
answered Jul 17, 2009 by solutionyogi
str = str.replace(/abc/g, '');

Or try the replaceAll function from here:

What are useful JavaScript methods that extends built-in objects?

str = str.replaceAll('abc', ''); OR

var search = 'abc';
str = str.replaceAll(search, '');

EDIT: Clarification about replaceAll availability

The 'replaceAll' method is added to String's prototype. This means it will be available for all string objects/literals.

E.g.

var output = "test this".replaceAll('this', 'that');  //output is 'test that'.
output = output.replaceAll('that', 'this'); //output is 'test this'
+22 votes
answered Jul 17, 2009 by donnie-deboer

Use a regular expression:

str.replace(/abc/g, '');
+1147 votes
answered Jul 17, 2009 by matthew-crumley

Note: Don't use this in real code.

As an alternative to regular expressions for a simple literal string, you could use

str = "Test abc test test abc test...".split("abc").join("");

The general pattern is

str.split(search).join(replacement)

This used to be faster in some cases than using replaceAll and a regular expression, but that doesn't seem to be the case anymore in modern browsers. So, this should really only be used as a quick hack to avoid needing to escape the regular expression, not in real code.

+3 votes
answered Oct 28, 2011 by vitim-us

My implementation, very self explanatory

function replaceAll(string, token, newtoken) {
    if(token!=newtoken)
    while(string.indexOf(token) > -1) {
        string = string.replace(token, newtoken);
    }
    return string;
}
+73 votes
answered Mar 1, 2012 by elias-van-ootegem

Update:

It's somewhat late for an update, but since I just stumbled on this question, and noticed that my previous answer is not one I'm happy with. Since the question involved replaceing a single word, it's incredible nobody thought of using word boundaries (\b)

'a cat is not a caterpillar'.replace(/\bcat\b/gi,'dog');
//"a dog is not a caterpillar"

This is a simple regex that avoids replacing parts of words in most cases. However, a dash - is still considered a word boundary. So conditionals can be used in this case to avoid replacing strings like cool-cat:

'a cat is not a cool-cat'.replace(/\bcat\b/gi,'dog');//wrong
//"a dog is not a cool-dog" -- nips
'a cat is not a cool-cat'.replace(/(?:\b([^-]))cat(?:\b([^-]))/gi,'$1dog$2');
//"a dog is not a cool-cat"

basically, this question is the same as the question here: Javascript replace " ' " with " '' "

@Mike, check the answer I gave there... regexp isn't the only way to replace multiple occurrences of a subsrting, far from it. Think flexible, think split!

var newText = "the cat looks like a cat".split('cat').join('dog');

Alternatively, to prevent replacing word parts -which the approved answer will do, too! You can get around this issue using regular expressions that are, I admit, somewhat more complex and as an upshot of that, a tad slower, too:

var regText = "the cat looks like a cat".replace(/(?:(^|[^a-z]))(([^a-z]*)(?=cat)cat)(?![a-z])/gi,"$1dog");

The output is the same as the accepted answer, however, using the /cat/g expression on this string:

var oops = 'the cat looks like a cat, not a caterpillar or coolcat'.replace(/cat/g,'dog');
//returns "the dog looks like a dog, not a dogerpillar or cooldog" ?? 

Oops indeed, this probably isn't what you want. What is, then? IMHO, a regex that only replaces 'cat' conditionally. (ie not part of a word), like so:

var caterpillar = 'the cat looks like a cat, not a caterpillar or coolcat'.replace(/(?:(^|[^a-z]))(([^a-z]*)(?=cat)cat)(?![a-z])/gi,"$1dog");
//return "the dog looks like a dog, not a caterpillar or coolcat"

My guess is, this meets your needs. It's not fullproof, of course, but it should be enough to get you started. I'd recommend reading some more on these pages. This'll prove useful in perfecting this expression to meet your specific needs.

http://www.javascriptkit.com/jsref/regexp.shtml

http://www.regular-expressions.info


Final addition:

Given that this question still gets a lot of views, I thought I might add an example of .replace used with a callback function. In this case, it dramatically simplifies the expression and provides even more flexibility, like replacing with correct capitalisation or replacing both cat and cats in one go:

'Two cats are not 1 Cat! They\'re just cool-cats, you caterpillar'
   .replace(/(^|.\b)(cat)(s?\b.|$)/gi,function(all,char1,cat,char2)
    {
       //check 1st, capitalize if required
       var replacement = (cat.charAt(0) === 'C' ? 'D' : 'd') + 'og';
       if (char1 === ' ' && char2 === 's')
       {//replace plurals, too
           cat = replacement + 's';
       }
       else
       {//do not replace if dashes are matched
           cat = char1 === '-' || char2 === '-' ? cat : replacement;
       }
       return char1 + cat + char2;//return replacement string
    });
//returns:
//Two dogs are not 1 Dog! They're just cool-cats, you caterpillar
+86 votes
answered Feb 11, 2013 by jesal

Here's a string prototype function based on the accepted answer:

String.prototype.replaceAll = function (find, replace) {
    var str = this;
    return str.replace(new RegExp(find, 'g'), replace);
};

EDIT

If your find will contain special characters then you need to escape them:

String.prototype.replaceAll = function (find, replace) {
    var str = this;
    return str.replace(new RegExp(find.replace(/[-\/\\^$*+?.()|[\]{}]/g, '\\$&'), 'g'), replace);
};

Fiddle: http://jsfiddle.net/cdbzL/

+8 votes
answered May 15, 2013 by owen

I like this method (it looks a little cleaner):

text = text.replace(new RegExp("cat","g"), "dog"); 
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