使用vue：
<select v-model="action_type" @change="type" class="action_type">
<option disabled value="">请选择</option>
<option>选项1</option>
<option>选项2</option>
</select>
html中：
<select v-model="action_type" @change="type" class="action_type">
<option disabled selected hidden>请选择</option>
<option>徒步</option>
<option>警车</option>
</select>
