Reuse Patterns Using Capture Groups

Summary

• Parentheses are used to find repeat substrings.
• To specify where that repeat string will appear, use a backslash and then a number.

Final Code

let repeatNum = "42 42 42";
let reRegex = /^(\d+)\s\1\s\1$/; // Change this line
let result = reRegex.test(repeatNum);