hasOwnProperty.call js

var person = {	
  	"first_name": "Bob",
	"last_name": "Dylan"
};
person.hasOwnProperty('first_name'); //returns true
person.hasOwnProperty('age'); //returns falsevar foo = {
  hasOwnProperty: function() {
    return false;
  },
  bar: 'I belong to foo'
};