php - 如何将2个选择元素组合在一起html

Question

我正在制作一个网站，我想将 2 个选择元素组合在一起。我的意思是在另一个里面有一个选择选项。在子选择中，用户可以选择多个选项。这就是我的意思(那行不通):

<select>
 <option value="1">
  <select>
   <option value="11">11 text</option>
   <option value="12">22 text</option>
  </select>
 </option>
 <option value="2">
  <select>
   <option value="21">21 text</option>
   <option value="22">22 text</option>
  </select>
 </option>
 <option value="3">
  <select>
   <option value="31">31 text</option>
   <option value="32">32 text</option>
  </select>
 </option>
</select>

提前感谢您的 awnser，尼科斯科

Answer 1

Optgroup 看起来像这样。这符合您的需求吗？

// '<value>': '<text>'
var group_members = {
  '1': {
    '11': '11',
    '12': '12',
  },
  '2': {
    '21': '21',
    '22': '22',
  },
  '3': {
    '31': '31',
    '32': '32',
  },
};

$('select[name=group]').on('change', function() {
  var $selectMember = $('select[name=group_member]');
  
  // clear options
  $selectMember.find('optgroup').remove();
  $selectMember.find('option').remove();
  
  // source here is 'group_members'
  // if you have much data i recommend using ajax here to query data by a script
  // as JSON have a look at AJAX - jQuery.ajax
  var selectedGroups = $(this).val();
  
  for(var i in selectedGroups) {
    var selectedGroup = selectedGroups[i];
    var optgroup = $('<optgroup>').attr('label', selectedGroup);
    
    for(var value in group_members[selectedGroup]) {
      optgroup
        .append(
          ($('<option>', { value: value })
            .text(group_members[selectedGroup][value]))
        );
    }
    $selectMember.append(optgroup);
  }
});

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>

Hold ctrl to select multiple
<hr />

Group:
<select name="group" multiple size=5>
  <option value=''>Please Select</option>
  <option value="1">1</option>
  <option value="2">2</option>
  <option value="3">3</option>
</select>

Group Members:
<select name='group_member' size=5 multiple></select>