Symbol.iterator.js

var arr = ['Sacha', 'Og', 'Haru'];
arr[Symbol.iterator] = function *() {
  var i = this.length - 1;
  while (i >= 0) {
    yield this[i];
    i--;
  }
}

for (var value of arr) {
  console.log(value);
}

console.log([...arr]);