自己筆記，防止忘記

<select class="form-control" data-edit-select="1" id="add_categoryId" name="categoryId" onmousedown="if(this.options.length>7){this.size=8}" onblur="this.size=0" onchange="this.size=0" >           <c:forEach var="category" items="${category}">                 <option value="${category.categoryId}">${category.value}</option>           </c:forEach>   </select>