String

`String.prototype.replace`

Returns a new string with one or all matches of a pattern replaced by a replacement

Syntax

JavaScript

string.replace(pattern, replacement)

Parameters

Parameter	Type	Description
pattern	string \| RegExp	The pattern to search for
replacement	string \| Function	The replacement string or function

Return Value

A new string with the replacement(s) made

Examples

Basic Usage

const str = 'Hello World';
console.log(str.replace('World', 'JS')); // 'Hello JS'

Practical Example

const date = '2024-01-15';
const formatted = date.replace(/(\d{4})-(\d{2})-(\d{2})/, '$2/$3/$1');
console.log(formatted); // '01/15/2024'

Advanced Usage

const text = 'foo bar foo';
const result = text.replace(/foo/g, 'baz');
console.log(result); // 'baz bar baz'

Understanding String.prototype.replace

The String.prototype.replace method in JavaScript returns a new string with one or all matches of a pattern replaced by a replacement. It belongs to the String object and is one of the most widely used methods for working with string values in modern JavaScript and TypeScript applications.

The method signature is string.replace(pattern, replacement). It accepts 2 parameters: pattern, replacement. When called, it returns a new string with the replacement(s) made. Understanding when and how to use replace() helps you write more expressive, readable code.

Common use cases for String.prototype.replace include data transformation, input validation, API response processing, and building reusable utility functions. It works well alongside related methods like string-replaceall, string-match, string-search, enabling you to chain operations together for complex data manipulation pipelines.

Browser support for String.prototype.replace is excellent across all modern browsers including Chrome, Firefox, Safari, and Edge. It is also fully supported in Node.js and Deno. For older environments, transpilation with Babel or a polyfill may be needed.