select2 js 加载

<!-- 引入 jQuery -->
<script src="https://code.jquery.com/jquery-3.6.0.min.js"></script>
<!-- 引入 select2 CSS -->
<link href="https://cdn.jsdelivr.net/npm/select2@4.1.0-rc.0/dist/css/select2.min.css" rel="stylesheet" />
<!-- 引入 select2 JS -->
<script src="https://cdn.jsdelivr.net/npm/select2@4.1.0-rc.0/dist/js/select2.min.js"></script>

<!-- 初始化 select2 -->
<select id="mySelect">
  <option value="1">Option 1</option>
  <option value="2">Option 2</option>
</select>

<script>
  $(document).ready(function() {
    $('#mySelect').select2();
  });
</script>

$('#mySelect').select2({
  ajax: {
    url: 'https://api.example.com/options',
    dataType: 'json',
    delay: 250,
    data: function (params) {
      return {
        q: params.term, // 搜索关键词
        page: params.page
      };
    },
    processResults: function (data, params) {
      params.page = params.page || 1;
      return {
        results: data.items,
        pagination: {
          more: (params.page * 30) < data.total_count
        }
      };
    },
    cache: true
  },
  minimumInputLength: 1
});