add #times to String prototype

string_prototype_times.js

​String.prototype.times = function(n) {
  // join checks its first argument for a length property, so we supply it with one.
  // what normally happens is something like this:
  //
  //   [1, 2, 3].length //=> 3
  //   [1, 2, 3].join(", ") //=> "1, 2, 3"
  //
  // so the following is equivalent ...
  //
  //  Array.prototype.join.call([1, 2, 3], ", ") //=> "1, 2, 3"
  //
  // we can even do:
  //
  //  Array.prototype.join.call({'0' : 1, '1' : 2, '2' : 3, length : 3}, ", ") //=> "1, 2, 3"
  //
  // so then just passing in an object with a length property of n + 1 will tell the Array
  // to join all indexed elements in the object (of which there are none) with the second argument
  // (the separator), which will result in the separator being concatenated n + 1 times, which
  // is then returned. Pretty tricky!
  return Array.prototype.join.call({length: n+1}, this);
}
    
console.log("join this ".times(10));