js禁用了上拉框怎樣啟用

js禁用了下拉框怎樣啟用
<select disabled="disabled" >
<option>aa</option>
<option>bb</option>
我是這樣把它禁用的,我想用腳本把它啟用,那應該怎樣寫?

[解决办法]
<select disabled="disabled" id="test" >
<option> aa </option>
<option> bb </option> 
</select>
<input type="button" value="启用" onclick="document.getElementById('test').disabled = false">
[解决办法]
<select disabled="disabled" id="mySel"> 
JS:
mySel.disabled = false;