HTML元素 - optgroup [ 用optgroup标签来分类select菜单]

</OPTGROUP>

<OPTGROUP LABEL="卤素">

<OPTION>氟 (F)</OPTION>

<OPTION>氯 (Cl)</OPTION>

<OPTION>溴 (Br)</OPTION>

</OPTGROUP>

</Select>

HTML代码 <select> <optgroup label="碱性金属"> <option>锂 (Li)</option> <option>纳 (Na)</option> <option>钾 (K)</option> </optgroup> <optgroup label="卤素"> <option>氟 (F)</option> <option>氯 (Cl)</option> <option>溴 (Br)</option> </optgroup> </select>

[Ctrl+A 全部选择 提示：你可先修改部分代码，再按运行]