判断值在下拉框中是否存在

test.aspx.cs代码 AJAX

protected void Gettestlist()
        {
            System.Data.DataTable dt = new System.Data.DataTable();
            dt.Columns.Add("subID", typeof(int));
            dt.Columns.Add("subName", typeof(string));
            dt.Columns.Add("examID", typeof(int));
            dt.Columns.Add("examName", typeof(string));
            dt.Rows.Add(new object[] { 1, "一班", 10, "语文" });
            dt.Rows.Add(new object[] { 1, "一班", 11, "数学" });
            dt.Rows.Add(new object[] { 2, "高二班", 10, "语文" });
            dt.Rows.Add(new object[] { 2, "高二班", 11, "数学" });

            System.Text.StringBuilder builder = new System.Text.StringBuilder();
            for (int i = 0; i < dt.Rows.Count; i++)
            {
                builder.Append(",{" + string.Format("'subID':'{0}','subName':'{1}','examID':'{2}','examName':'{3}'", dt.Rows[i]["subID"], dt.Rows[i]["subName"], dt.Rows[i]["examID"], dt.Rows[i]["examName"]) + "}");
            }
            if (builder.Length > 0)
            {
                builder.Remove(0, 1);
                builder.Insert(0, "[");
                builder.Append("]");
            }
            Response.Write(builder);
            Response.End();
        }

test.aspx --- JS

function BindSubList()
{
    var url="ExportData.aspx?ajaxtype=test&tt=tt";
    var result = $.ajax({url:url,async:false}).responseText;   
     if(result && result.length > 0) //如果读取数据成功，就清除下级商品分类的内容，绑定当前分类的内容
     {
        var sortFactory = eval(result);
        var control = $("#selsub");
        control.get(0).options.length = 0;
        var retcheck=false;
        for(var i =0 ; i < sortFactory.length; i++)
        { 
            retcheck = false;
            for  (var j = 0 ; j < control[0].options.length; j++)
            {
                if (control[0].options[j].value == sortFactory[i].subID)
                {
                    retcheck=true;
                    break;
                }
            }         
            if(!retcheck)
              control.get(0).options.add(new Option(sortFactory[i].subName,sortFactory[i].subID));
        }
     }
}

 

 

test.aspx--html

<select id="selsub">
                    <option id="0">请选择</option>
                </select>