Skip to content

JavaScript regex match group | Example code

  • by

Using the JavaScript RegEx match group will help to find the multiple times. It is wasteful to repeat that regex manually. A better way to specify multiple repeated substrings is using the “RegEx Capturing Groups” in the match() method.


JavaScript regex match group

Simple example code searching in the string for patterns. Parentheses ( ), are used to find repeated substrings. We just need to put the regex that will repeat in between the parentheses.

<!DOCTYPE html>
    let regex = /(go)+/ig;
    let str = 'goGoGOgOgoooogo';

    let result = str.match(regex);



JavaScript regex match group | Example code

Specify RegEx Capturing Groups using Numbers

let repeatNum = "93 93 93";
let wrongNum = "100 100 200 100";

let regex = /^(\d+)\s\1\s\1$/;

let result = regex.test(repeatNum);
console.log(result); //true

result = repeatNum.match(regex);
console.log(result); // [ '93 93 93' ]

let wrongRes = regex.test(wrongNum);
console.log(wrongRes); //false

wrongRes = wrongNum.match(regex);
console.log(wrongRes); //null


Specify RegEx Capturing Groups using Numbers

/^(\d+)\s\1\s\1$/ this regex explains:

  • A caret ( ^ ) is at the beginning of the entire regular expression, it matches the beginning of a line.
  • (\d+) is the first capturing group that finds any digit from 0-9 appears at least one or more times in the string?
  • \s finds a single white space
  • \1 represents the first capturing group which is (\d+).
  • A dollar sign ( $ ) is at the end of the entire regular expression, it matches the end of a line.

Capturing groups in replacement

Method str.replace(regexp, replacement) that replaces all matches with regexp in str allows using of parentheses contents in the replacement string. That’s done using $n, where n is the group number.

let str = "John Bull";
let regexp = /(\w+) (\w+)/;

alert( str.replace(regexp, '$2, $1') ); // Bull, John

Do comment if you have any doubts or suggestions on this JS match topic.

Note: The All JS Examples codes are tested on the Firefox browser and the Chrome browser.

OS: Windows 10

Code: HTML 5 Version

Leave a Reply

Your email address will not be published. Required fields are marked *