Answers for "duplicate an array in javascript n times"

duplicate an array in javascript n times

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

duplicate numbers in an array javascript

[1, 1, 2, 2, 3].filter((element, index, array) => array.indexOf(element) !== index) // [1, 2]