JavaScript .match()

The .match() method searches a string for matches against a regular expression and returns the result as an array object. The .match() method is used in JavaScript to find parts of a string that match a regular expression. It is commonly applied in tasks such as extracting numbers or words, validating formats like email addresses, or parsing structured text.

Syntax

string.match(regex)

Parameters:

• regex: A regular expression object to match against the string.

Return value:

• If the regular expression has the g flag: Returns an array of all matches found, or null if no match is found.
• Without the g flag: Returns an array with detailed information about the first match (including captured groups), or null if no match is found.

Example 1: Using .match() to Find Uppercase Letters in a String

In the following example, a string variable paragraph contains a sentence, and regex defines a regular expression to match all uppercase letters. The .match() method applies this regex to the string and returns an array of all matches:

const paragraph = 'The quick brown fox jumps over the lazy dog. It barked.';
const regex = /[A-Z]/g;
console.log(paragraph.match(regex));

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The output of this code will be:

[ 'T', 'I' ]

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If the “g” flag is not used, it returns the array object with the result at index 0:

const paragraph = 'The quick brown fox jumps over the lazy dog. It barked.';
const regex = /[A-Z]/;
console.log(paragraph.match(regex));

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The output of this code will be:

[
  'T',
  index: 0,
  input: 'The quick brown fox jumps over the lazy dog. It barked.',
  groups: undefined
]

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Example 2: Finding All Occurrences of a Word Using .match()

This example demonstrates how to use the .match() method to find all occurrences of the word “Hello” in a string:

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The output of this code is:

[ 'Hello', 'Hello' ]

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