<form name="testform">
<select name="testselect">
<option value="first">first option</option>
<option value="second">second option</option>
<option value="third">third option</option>
<option>your browser can't handle this script</option>
</select>
</form>

// 得到選項(xiàng)對(duì)象
document.forms['testform'].testselect.options[i]

document.forms['testform'].testselect.options[i] = null;

document.forms['testform'].testselect.options[i] = new Option('new text','new value');

document.forms['testform'].testselect.option.length = 0;