snippetjavascriptTip

Replace all occurrences of a string in JavaScript

Submitted by: @import:30-seconds-of-code·Mar 2, 2026·

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javascriptreplacealloccurrencesstring

Problem

Modern JavaScript engines have a built-in method called String.prototype.replaceAll(). This method can be used to replace all occurrences of a string in another string with relative ease.
Using String.prototype.replaceAll() is the recommended approach, as it's straightforward. If, however, you need to support older browsers, consider the option below.
Before the introduction of String.prototype.replaceAll(), String.prototype.replace() was the method of choice for this sort of task. It's supported by all JavaScript engines, old and new and is very similar to String.prototype.replaceAll().
While this method doesn't replace all occurrences of a string, it supports regular expressions. Knowing the string to be replaced, a regular expression can be created with the global ('g') flag. Then, it can be passed to String.prototype.replace() to replace all occurrences of the string. The only issue here is that special characters need to be escaped, so that they are matched correctly. The escapeRegExp code snippet comes in handy for this task.

Solution

const str = 'Hello World';

str.replaceAll('o', 'x'); // 'Hellx Wxrld'

Before the introduction of String.prototype.replaceAll(), String.prototype.replace() was the method of choice for this sort of task. It's supported by all JavaScript engines, old and new and is very similar to String.prototype.replaceAll().
While this method doesn't replace all occurrences of a string, it supports regular expressions. Knowing the string to be replaced, a regular expression can be created with the global ('g') flag. Then, it can be passed to String.prototype.replace() to replace all occurrences of the string. The only issue here is that special characters need to be escaped, so that they are matched correctly. The escapeRegExp code snippet comes in handy for this task.

Code Snippets

const str = 'Hello World';

str.replaceAll('o', 'x'); // 'Hellx Wxrld'

const escapeRegExp = str => str.replace(/[.*+?^${}()|[\]\\]/g, '\\$&');
const replaceAll = (str, subStr, newSubStr) =>
  str.replace(new RegExp(escapeRegExp(subStr), 'g'), newSubStr);

const str = 'Hello World';

replaceAll(str, 'o', 'x'); // 'Hellx Wxrld'

Context

From 30-seconds-of-code: replace-all-occurences-of-string

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