How to repeat an array in JavaScript

In this Article we will go through how to repeat an array 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 repeat = (arr, n) => [].concat(...Array(n).fill(arr));

Parameters arr is an array.

const repeat = (arr, n) => Array(n).fill(arr).flat();

const repeat = (arr, n) => Array(arr.length * n).fill(0).map((_, i) => arr[i % arr.length]);

const repeat = (arr, n) => Array.from({ length: arr.length * n }, (_, i) => arr[i % arr.length]);

repeat([1, 2, 3], 3);       // [1, 2, 3, 1, 2, 3, 1, 2, 3]