Replace all occurrences of a substring in a string using JavaScript

This post will discuss how to replace all occurrences of a substring in a given string using JavaScript.

There is no native replaceAll() method in JavaScript which replaces all matches of a substring by a replacement. This post provides an overview of some of the available alternatives to accomplish this.

1. Using Regular Expression

The general strategy for replacing a substring in the given string is with the replace() method. However, the replace() method only removes the first occurrence of the substring. The idea is to pass a RegExp object to the replace() method to replace all occurrences.

Here’s a working example with the regular expression defined in the replace() method.

String.prototype.replaceAll = function(search, replacement) {

return this.replace(new RegExp(search, 'g'), replacement);

};

const str = 'Hello World 123';

console.log(str.replaceAll(" ", ""));

Output: HelloWorld123

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2. Using `Split()` with `Join()` method

Another approach is to split the string using the given substring as a delimiter and then join it back together with the replacement string. This would translate to a simple code below:

String.prototype.replaceAll = function(search, replacement) {

return this.split(search).join(replacement);

};