Minimalist extend function

extend.js

function extend() { 
  var i, prop, source;
  var args = Array.prototype.slice.call(arguments);
  var destination = args.shift();

  for (i=0; i<args.length; i++) {
    source = args[i];

    for (prop in source) {
      destination[prop] = source[prop];
    }
  }

  return destination;
}