JavaScript实现下拉框动态切换图片

<html>
<title>下拉框选择要显示的图片</title>
<body>
<img width=320 height=240 src="images/m01.jpg" name="x1"> 
<SELECT onChange="document.x1.src=options[selectedIndex].value"> 
<option value="images/m04.jpg">油菜花开</option> 
<option value="images/m03.jpg">往事如茶</option> 
<option value="images/m02.jpg">野花绽放</option> 
<option value="images/m01.jpg">红叶传情</option> 
</SELECT> 
</body>
</html>