var a = { name: 123};var b = a;a.name;123b.name;123a.name = ‘wolf‘;"wolf"b.name"wolf"a.name = null;  //注销此引用对象的内存，引用此引用对象的对象，失去对引用对象的引用，获得属于自己的引用对象副本;nullb.namenulla = null;nullbObject {name: null}