如果你的方法不带参数，就不要在ajax调用上指定data属性

If your method takes no arguments, just don't specify the data property on the ajax call

<script>
  $(function () {
    $.ajax({
      url: 'WebService.asmx/getList',
      type: 'POST',
      dataType: 'json', //make sure your service is actually returning json here
      contentType: 'application/json',
      success: function (data, status) {
        //here data is whatever your WebService.asmx/getList returned
        //populate your dropdown here with your $.each w/e
      }
    });
  });
</script>

我也错了，但是你展示的WebService方法似乎不会返回JSON。我认为你必须序列化，或设置内容类型或类似的东西。 （自从我使用asmx类型服务以来一直沿着时间）

Also I could be wrong, but the WebService method you showed, doesn't look like it will return json. I think you will have to serialize, or set the content type or something similar. (Been along time since I've used the asmx type services)