C# 在js中获取控件的值

C# 中控件的代码

机种：<asp:DropDownList ID="ddl_Type" AutoPostBack="true" runat="server" Height="19px" Width="128px">
                <asp:ListItem Value="机种1">机种1</asp:ListItem>

JS中取值方法

let rate = document.getElementById("ddl_Type").value;

 

 

把值传入到.ashx页面并在.ashx页面取值

  $(document).ready(function () {
            $('#myButton').click(function () {
                var chartWidth = '45%'; // 设定图表宽度
                var chartHeight = '300px'; // 设定图表高度
                let dpDept = document.getElementById("dpDept").value;
                let ddl_Type = document.getElementById("ddl_Type").value;
                let ddl_Processes = document.getElementById("ddl_Processes").value;
                let ddl_Items = document.getElementById("ddl_Items").value;
                $.ajax({
                    type: "POST",
                    url: "GetEchartsMachineFirstData.ashx?dpDept=" + dpDept + "&ddl_Type=" + ddl_Type + "&ddl_Processes=" + ddl_Processes + "&ddl_Items=" + ddl_Items + "",
                    contentType: "application/json; charset=utf-8",
                    dataType: "json",
                    success: function (response) { },
                    error: function (xhr, status, error) {
                        console.error("AJAX request failed:", status, error);
                        console.log(xhr.responseText); // 打印服务器返回的错误信息
                    }
                });
            });
        });

取值页面（.ashx页面）

     string dpDept = context.Request.Params["dpDept"];
        string ddl_Type = context.Request.Params["ddl_Type"];
        string ddl_Processes = context.Request.Params["ddl_Processes"];
        string ddl_Items = context.Request.Params["ddl_Items"];