Javascript: 練習實作select，模仿ruby的select

gistfile1.js

Array.prototype.select = function(callback){
  count = this.length;
  results = new Array();
  for(i=0;i<count;i++){
    if(callback(this[i]))
      results.push(this[i]);
  }
  return results;
};

gg = [1,2,3,4,5,6,7,8,9]
//[1, 2, 3, 4, 5, 6, 7, 8, 9]
gg.select(function(i){return i%2==0});
//[2, 4, 6, 8]