how to return to the default sort javascript code example

Example 1: js index sorted

var test = ['b', 'c', 'd', 'a'];
var len = test.length;
var indices = new Array(len);
for (var i = 0; i < len; ++i) indices[i] = i;
indices.sort(function (a, b) { return test[a] < test[b] ? -1 : test[a] > test[b] ? 1 : 0; });
console.log(indices);

Example 2: sort js array array

var ages = [18, 21, 9, 41, 35, 24]
ages.sort(function(a, b) {
  return a - b
})
// => [9, 18, 21, 24, 35, 41]