How to check if a string consists of a repeated character sequence in JavaScript

In this Article we will go through how to check if a string consists of a repeated character sequence only using single line of code in JavaScript. This is a one-line JavaScript code snippet that uses one of the most popular ES6 features => Arrow Function.

Let's define this short function:

const consistsRepeatedSubstring = str => `${str}${str}`.indexOf(str, 1) !== str.length;

consistsRepeatedSubstring('aa');            // true
consistsRepeatedSubstring('aaa');           // true
consistsRepeatedSubstring('ababab');        // true
consistsRepeatedSubstring('abc');           // false