JavaScript Array#map

gistfile1.js

Array.prototype.map = function(func) { 
  var output = []
  for(i=0; i < this.length; i++) {
    output[i] = func(this[i])
  }
  return output
}

// Example usage:
// [1,2,3].map(function(i) { return i * i })
// returns [1, 4, 9]