<select id="select"></select>
<h4>最终效果</h4>
<select>
  <option value="4" label="a/a-2/index"></option>
  <option value="6" label="a/a-3/index"></option>
  <option value="8" label="b/index"></option>
  <option value="9" label="c"></option>
</select>