Object.create

var emptyObject = Object.create(null);

var emptyObject = Object.create(null);

var emptyObject = {};

var emptyObject = new Object();

区别:

var o;  
  
// create an object with null as prototype  
o = Object.create(null);  
  
  
o = {};  
// is equivalent to:  
o = Object.create(Object.prototype);  
  
  
function Constructor(){}  
o = new Constructor();  
// is equivalent to:  
o = Object.create(Constructor.prototype);  
// Of course, if there is actual initialization code in the Constructor function, the Object.create cannot reflect it  
  
  
// create a new object whose prototype is a new, empty object  
// and a adding single property 'p', with value 42  
o = Object.create({}, { p: { value: 42 } })  
  
// by default properties ARE NOT writable, enumerable or configurable:  
o.p = 24  
o.p  
//42  
  
o.q = 12  
for (var prop in o) {  
   console.log(prop)  
}  
//"q"  
  
delete o.p  
//false  
  
//to specify an ES3 property  
o2 = Object.create({}, { p: { value: 42, writable: true, enumerable: true, configurable: true } });

https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Object/create