Repeat an array with multiple elements multiple times in JavaScript

Question

No need for any library, you can use Array.from to create an array of arrays you want repeated, and then flatten using [].concat and spread:

const makeRepeated = (arr, repeats) =>
  [].concat(...Array.from({ length: repeats }, () => arr));
  
console.log(makeRepeated([1, 2, 3], 2));

On newer browsers, you can use Array.prototype.flat instead of [].concat(...:

const makeRepeated = (arr, repeats) =>
  Array.from({ length: repeats }, () => arr).flat();
  
console.log(makeRepeated([1, 2, 3], 2));