CODE EXAMPLE FOR JAVASCRIPT

what is last index of array

const indices = [];
const array = ['a', 'b', 'a', 'c', 'a', 'd'];
const element = 'a';
let idx = array.lastIndexOf(element);
while (idx !== -1) {
  indices.push(idx);
  idx = (idx > 0 ? array.lastIndexOf(element, idx - 1) : -1);
}

console.log(indices);
// [4, 2, 0]