我想使用ajax在combobox中使用数据库获取动态值

Question

<script src="https://code.jquery.com/jquery-1.12.4.js"></script>
<script type="text/javascript">
  function getSubject() {
    var yr=document.getElementById("semester").value;
    console.log(yr);

    $.ajax({
      type: "GET",
      url: "dropdown.php",
      data: "yr="+yr,
      success: function(result) {
        $("#subject").html(result);
      }
    });
  }
</script>

根据年度学期选择年份必须使用ajax

加载另一个组合框

Answer 1

$('#semester').change(function () {

        $('#subject').html('<option value="" id="0">Select Subject</option>');
        var yr=$(this).val();

        $.ajax({
            data: {'yr' : yr},
            type: "GET",
            url : "dropdown.php",
            dataType:'json',
            success:function(data)
            {   
                for (var i = 0; i < data.length; i++) {

                    var result = '<option value="'+data[i]['sem_id']+'">'+data[i]['sem_name']+'</option>'
                    $('#subject').append(result);
                }
            },
            error:function()
            {
                alert("Something Wrong..");
            }
        });
    });