Changing the value of an object in a var

var obj1 = { id: 1, name: 'abc' };
        var obj2 = { id: 2, name: 'xyx' };
        var ary = [];
        ary.push(obj1);
        ary.push(obj2);
        ary[1].id = 3;
        ary[1].name = 'new name';
        alert(obj2.id + ' -- ' +obj2.name); // 3 -- new name
        alert(ary[1].id + ' -- ' + ary[1].name); // 3 -- new name

var a = 1;
      var b = 2;
      var ary = [];
      ary.push(a);
      ary.push(b);
      ary[1] = 3;
      alert(b); // 2
      alert(ary[1]); // 3