JavaScript RegExp exec()
Syntax & Examples

RegExp.exec() method

The exec() method of the RegExp object in JavaScript executes a search for a match in a specified string. This method returns an array containing the matched results, or null if no match is found.

Syntax of RegExp.exec()

The syntax of RegExp.exec() method is:

exec(str)

This exec() method of RegExp executes a search for a match in its string parameter. Returns an array containing the matched results or null if no match is found.

Parameters

ParameterOptional/RequiredDescription
strrequiredThe string against which to match the regular expression.

Return Type

RegExp.exec() returns value of type Array.


✐ Examples

1 Using exec() to find a match in a string

In JavaScript, we can use the exec() method to find a match in a string. The method returns an array with the matched results.

For example,

  1. We create a RegExp object regex with the pattern /hello/.
  2. We use the exec() method to search for the pattern in the string 'hello world'.
  3. The result is stored in the variable result and we log it to the console.

JavaScript Program

const regex = /hello/;
const result = regex.exec('hello world');
console.log(result);

Output

[ 'hello', index: 0, input: 'hello world', groups: undefined ]

2 Using exec() with a global pattern

In JavaScript, we can use the exec() method with a global pattern to find multiple matches in a string.

For example,

  1. We create a RegExp object regex with the global pattern /\d+/g to match one or more digits.
  2. We use the exec() method in a loop to find all matches in the string '123 456 789'.
  3. Each match is logged to the console.

JavaScript Program

const regex = /\d+/g;
let result;
while ((result = regex.exec('123 456 789')) !== null) {
  console.log(result);
}

Output

[ '123', index: 0, input: '123 456 789', groups: undefined ]
[ '456', index: 4, input: '123 456 789', groups: undefined ]
[ '789', index: 8, input: '123 456 789', groups: undefined ]

3 Using exec() to extract groups from a match

In JavaScript, we can use the exec() method to extract groups from a matched string.

For example,

  1. We create a RegExp object regex with the pattern /(\w+)\s(\w+)/ to match two words separated by a space.
  2. We use the exec() method to search for the pattern in the string 'hello world'.
  3. The result is stored in the variable result and we log the matched groups to the console.

JavaScript Program

const regex = /(\w+)\s(\w+)/;
const result = regex.exec('hello world');
console.log(result[0]); // 'hello world'
console.log(result[1]); // 'hello'
console.log(result[2]); // 'world'

Output

hello world
hello
world

Summary

In this JavaScript tutorial, we learned about exec() method of RegExp: the syntax and few working examples with output and detailed explanation for each example.