怎么用函数传递类名啊。帮帮忙

Question

代码如下：
-------------------------------------------------------------------------------------------------------
<div id="ID_Name_1" onmouseover="change_bg()">hello world.</div>
<div id="ID_Name_2" onmouseover="chnage_bg()">hello china.</div>
<script type="text/javascript">
    function change_bg() {
        document.getElementById().style.background="url(/images/image_name.jpg)";
    }
</script>
--------------------------------------------------------------------------------------------------------我是想当鼠标移动到两个DIV上，他们的背景图片变为image_name.jpg。我该怎么实现呢？还有我写成
---------------------------------------------------------------------------------------------------------
<div id="ID_Name_1" onmouseover="change_bg(this)">hello world.</div>
<div id="ID_Name_2" onmouseover="chnage_bg(this)">hello china.</div>
<script type="text/javascript">
    function change_bg(this) {
        document.getElementById(this).style.background="url(/images/image_name.jpg)";
    }
</script>
----------------------------------------------------------------------------------------------------------
报错了，为什么啊？this不能传递ID名吗？

Answer 1

<div   id= "ID_Name_1 "   onmouseover= "change_bg(this) "> hello   world. </div> 
<div   id= "ID_Name_2 "   onmouseover= "chnage_bg(this) "> hello   china. </div> 
<script   type= "text/javascript "> 
        function   change_bg(ele)   { 
alert(ele.style.background)
                ele.style.background= "url(/images/image_name.jpg) "; 
        } 
</script> 

Answer 2

报错了，为什么啊？this不能传递ID名吗？ --------------------------------------不是ID 是当前对象~·

Answer 3

<div   id= "ID_Name_1 "   onmouseover= "change_bg(this.id) "> hello   world. </div> 
<div   id= "ID_Name_2 "   onmouseover= "chnage_bg(this.id) "> hello   china. </div> 
<script   type= "text/javascript "> 
        function   change_bg(id)   { 
                document.getElementById(id).style.background= "url(/images/image_name.jpg) "; 
        } 
</script> 
这样是传入ID   this.id

Answer 4

这里面的this 等于document.getElmentById("类名") 吗？

Answer 5

对~·this已经是当前对象了~·