var w, x;

​

Object.defineProperty(Object.prototype, 'intersect', {

  value: function(obj) {

    var k, t;

    t = {};

    for (k in obj) {

      t[k] = this[k];

    }

    return t;

  }

});

​

x = {

  a: 1,

  b: 2,

  c: 3,

  d: "33"

};

​

w = {

  a: 3,

  b: 4

};

​

console.log(x.intersect(w));