select 태그는 드롭다운 목록을 만들 때 사용합니다. 양식이 제출된 후 양식 데이터를 참조하려면 속성 name이 필요합니다. 속성을 생략하면 name드롭다운 목록의 데이터가 제출되지 않습니다.
<select name="pets" id="pets">
<option value="cats">cats</option>
<option value="dogs">dogs</option>
<option value="fishes">fishes</option>
<option value="birds">birds</option>
</select>
<select name="pets" id="pets">
<option selected value="=">pets</option>
<option value="dogs">dogs</option>
<option value="fishes">fishes</option>
<option value="birds">birds</option>
</select>
<select name="pets" required id="pets">
<option selected value="">pets</option>
<option value="dogs">dogs</option>
<option value="fishes">fishes</option>
<option value="birds">birds</option>
</select>
html
<select name="pets" required id="pets">
<option selected disabled value="">pets</option>
<option value="dogs">dogs</option>
<option value="fishes">fishes</option>
<option value="birds">birds</option>
</select>
css
select option[value=""][disabled] {
display: none;
}