RegExp

`RegExp.prototype.exec`

Executes a search for a match in a specified string and returns a result array or null

Syntax

JavaScript

regexp.exec(str)

Parameters

Parameter	Type	Description
str	string	The string against which to match

Return Value

An array with the matched text and captured groups, or null

Examples

Basic Usage

const regex = /(\d{4})-(\d{2})-(\d{2})/;
const result = regex.exec('Date: 2024-01-15');
if (result) {
  console.log(result[1]); // '2024'
  console.log(result[2]); // '01'
}

Practical Example

const regex = /\b(\w+)\b/g;
const str = 'hello world';
let match;
while ((match = regex.exec(str)) !== null) {
  console.log(match[1], 'at', match.index);
}

Advanced Usage

const regex = /(?<year>\d{4})-(?<month>\d{2})/;
const result = regex.exec('2024-06');
console.log(result?.groups?.year); // '2024'
console.log(result?.groups?.month); // '06'

Understanding RegExp.prototype.exec

The RegExp.prototype.exec method in JavaScript executes a search for a match in a specified string and returns a result array or null. It belongs to the RegExp object and is one of the most widely used methods for working with regexp values in modern JavaScript and TypeScript applications.

The method signature is regexp.exec(str). It accepts 1 parameter: str. When called, it returns an array with the matched text and captured groups, or null. Understanding when and how to use exec() helps you write more expressive, readable code.

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

Browser support for RegExp.prototype.exec 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.