js 获取属性名称

$(function ()
        {
            myfun();
        })
        function myfun()
        {
            var aa = { "a": [{ "b": "c" }, { "b": "f" }] };
            var obj = eval(aa);
            //var obj = { a: 1, b: 2, c: 3 }
            for (var p in obj.a[0])
            {   //p是属性名称
                var s = obj.a[0][p]
                alert(obj.a[0][p]);
        }
        }