String.prototype.replace() - JavaScript | MDN

Can be a string or an object with a Symbol.replace method — the typical example being a regular expression. Any value that doesn't have the Symbol.replace method will be coerced to a string.

RegExp.prototype[Symbol.replace]()

This method does not mutate the string value it's called on. It returns a new string.

the regular expression guide

Note: See the regular expression guide for more explanations about regular expressions.

Switching words in a string

The following script switches the words in the string. For the replacement text, the script uses capturing groups and the $1 and $2 replacement patterns.

Using an inline function that modifies the matched characters

In this example, all occurrences of capital letters in the string are converted to lower case, and a hyphen is inserted just before the match location. The important thing here is that additional operations are needed on

Making a generic replacer

Suppose we want to create a replacer that appends the offset data to every matched string. Because the replacer function already receives the offset parameter, it will be trivial if the regex is statically known.

String.prototype.replaceAll()

String.prototype.match()

RegExp.prototype.exec()

RegExp.prototype.test()

Learn how to contribute

This page was last modified on Apr 12, 2026 by MDN contributors.

toLocaleLowerCase()

toLocaleUpperCase()

[Symbol.iterator]()

[Symbol.hasInstance]()

__defineGetter__()

⌂dev

1/1