Java Script对象字段访问

Question

var friends = new Object ();
friends.bill = new Object ();
    friends.bill.firstName = 'Bill';
    friends.bill.lastName = 'Gates';

friends.steve = new Object ();
    friends.steve.firstName = 'Steve';
    friends.steve.lastName = 'Jobs';



    var search1 = function (name) {
        for (var x in friends){
            if (name == friends.x.firstName) {

                console.log(friends.x.firstName, friends.x.lastName);

            }
        }
    }

var search2 = function (name) {
        for (var x in friends){
            if (name == friends[x].firstName) {

                console.log(friends[x].firstName, friends[x].lastName);

            }
        }
    }

有人可以解释为什么search2工作得很好（在同名朋友中打印对象的细节），但是search1不起作用。

我确定object.x与object [x]相同...... 如果没有，有什么区别？ 非常感谢！