Native "extensions" with jQuery?

Does anybody know this works?

by rpflorence

HTML

Run

JavaScript

jQuery.fn.sum = function(){
  var sum = 0;
  for (var i = this.length - 1; i >= 0; i--){
    sum += parseFloat(this[i]);
  };
  return sum;
};

var sum = $([1,2,3]).sum();

$('body').text(sum);