layui selsect下拉框選中

<form class="layui-form layui-form-pane" action=""  lay-filter="form_demo">
    <div class="layui-form-item">
         <label class="layui-form-label">實例</label>
         <div class="layui-input-inline">
              <select name="select_demo" id="select_demo">
                   {for start="1" end="11"}
                        option value="{$i}">{$i} 次</option>
                   {/for}
              </select>
         </div>
   </div>
</form>

<script>
    form.val('form_demo', {
        "select_demo": select_demo
    });
</script>