多个选择框使用 jquery 确认至少选择了一个选项

Question

I have a select box that I need to check with jquery on mouseleave if there's an option selected however suggestions like $('#category').attr("selectedIndex") returns undefined even when an option has been selected.

HTML below:

<select id="category" multiple="multiple" class="category">
    {% for category in categories %}
       <option value="{{ category.id }}">{{ category.name }}</option>
    {% endfor %}
</select>

I have Django dump a list of options so for the above options list. I'd prefer if the code can filter by select id category so for it doesn't intefer with any other select boxes.

Answer 1

You can try

$("#category option:selected").index()

or

$("#category").prop("selectedIndex")

I think .prop is for the newer versions of jquery.

Answer 2

$("#category").on('focusout',function() {
  console.log($(this).val());
});