pavel-lens

const array = [1, 2, 3, 4, 5];
const array2 = array.map((value) => value * 2);
console.log(array2); // [ 2, 4, 6, 8, 10 ]

pavel-lens

const array = [1, 2, 3, 4, 5];
for (let i=0; i < array.length; i++) {
  array[i] = array[i] * 2;
}
console.log(array); // [ 2, 4, 6, 8, 10 ]