The [@@replace]() method replaces some or all matches of a this pattern in a string by a replacement, and returns the result of the replacement as a new string. The replacement can be a string or a function to be called for each match.


regexp[Symbol.replace](str, newSubStr|function)


A String that is a target of the replacement.
newSubStr (replacement)
The String that replaces the substring. A number of special replacement patterns are supported; see the Specifying a string as a parameter section in String.prototype.replace() page.
function (replacement)
A function to be invoked to create the new substring. The arguments supplied to this function are described in the Specifying a function as a parameter section in String.prototype.replace() page.

Return value

A new string with some or all matches of a pattern replaced by a replacement.


This method is called internally in String.prototype.replace() if the pattern argument is a RegExp object.  For example, following two examples return same result.

'abc'.replace(/a/, 'A');

/a/[Symbol.replace]('abc', 'A');

This method exists for customizing replace behavior in RegExp subclass.

If pattern argument is not a RegExp object, String.prototype.replace() doesn't call this method, nor creates a RegExp object.


Direct call

This method can be used in almost the same way as String.prototype.replace(), except the different this and the different arguments order.

var re = /-/g; 
var str = '2016-01-01';
var newstr = re[Symbol.replace](str, '.');
console.log(newstr);  // 2016.01.01

Using @@replace in subclasses

Subclasses of RegExp can override the [@@replace]() method to modify the default behavior.

class MyRegExp extends RegExp {
  constructor(pattern, flags, count) {
    super(pattern, flags);
    this.count = count;
  [Symbol.replace](str, replacement) {
    // Perform @@replace |count| times.
    var result = str;
    for (var i = 0; i < this.count; i++) {
      result = RegExp.prototype[Symbol.replace].call(this, result, replacement);
    return result;

var re = new MyRegExp('\\d', '', 3);
var str = '01234567';
var newstr = str.replace(re, '#'); // String.prototype.replace calls re[@@replace].
console.log(newstr); // ###34567


ECMAScript (ECMA-262)
The definition of 'RegExp.prototype[@@replace]' in that specification.

Browser compatibility

Update compatibility data on GitHub
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidFirefox for AndroidOpera for AndroidSafari on iOSSamsung InternetNode.js
@@replaceChrome Full support 50Edge Full support 79Firefox Full support 49IE No support NoOpera Full support 37Safari Full support 10WebView Android Full support 50Chrome Android Full support 50Firefox Android Full support 49Opera Android Full support 37Safari iOS Full support 10Samsung Internet Android Full support 5.0nodejs Full support 6.0.0


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See also