Import object by values not references

jquery-importProp.js

;(function($){
  $.importProp = function($this, $src, subset) {
      if(subset){
          $.each(subset, function(i, key){
              $this[key] = $src[key];
          });
      } else {
          $.each($src, function(key, e){
              $this[key] = $src[key];
          });
      }
  };
})(jQuery);

var a = {p:"x"};
var b = {q:"y",r:"z",s:"a"};
$.importProp(a, b,["q","s"]);
console.log(a);