在昨天的《Javascript權(quán)威指南》學(xué)習(xí)筆記之十：ECMAScript 5 增強(qiáng)的對(duì)象模型一文中，對(duì)于一段代碼的調(diào)試出現(xiàn)了一個(gè)奇怪現(xiàn)象，現(xiàn)將源代碼貼在下面：

復(fù)制代碼 代碼如下:

<script type="text/javascript">
function Person(){}
var per = new Person;
Object.defineProperties(per,
{
"nickName":
{
value:"Tom",
writable:true
},
"age":
{
value:20,
configurable:false,
writable:false
}
});

var o = Object.getOwnPropertyDescriptor(per,"nickName");
alert(JSON.stringify(o));
</script>

復(fù)制代碼 代碼如下:

<script type="text/javascript">
function Person(){}
var per = new Person;
Object.defineProperties(per,
{
"nickName":
{
value:"Tom",
writable:true
},
"age":
{
value:20,
configurable:false,
writable:false
}
});

var name = Object.getOwnPropertyDescriptor(per,"nickName");
alert(JSON.stringify(name));
</script>