<html>
不是undefined呀<body>
<select name=el id=el>
<option value=1>文件</option>
<option value=2>编辑</option>
</select>
<script>
alert(el.multiple);
</script>
</body>
</html>
不是undefined呀<body>
<select name=el id=el>
<option value=1>文件</option>
<option value=2>编辑</option>
</select>
<script>
alert(el.multiple);
</script>
</body>
</html>
<body>
<select name=el id=el multiple>
<option value=1>文件</option>
<option value=2>编辑</option>
</select>
<script>
el.removeAttribute("multiple");
el.outerHTML = el.outerHTML;
</script>
</body>
</html>