JavaScript事件处理程序触发“错误：CS1026：）预期”异常

Question

I've created a table of dynamic controls which each row is a couple of (DropDownList and TextBox) then I've associated an event handler on each DropDownList selected change event so I can change on its TextBox as the code below shows :

DropDownList TypeDDL = new DropDownList();
    TypeDDL.ID = "TypeDDL_" + rowN.ToString();
    TypeDDL.Width = 120;
    TypeDDL.Height = 20;
    InitializeTypeDDL(TypeDDL);
    TypeDDL.AutoPostBack = true;
    TypeDDL.Attributes.Add("onchange", "javascript:handleFieldsDDLEvent(this);");
    TextBox FieldsDDL = new TextBox();
    FieldsDDL.ID = "FieldsDDL_" + rowN.ToString();
    FieldsDDL.Width = 120;
    FieldsDDL.Height = 20;
    FieldsDDL.Attributes.Add("style", "float:right");

but the Javascript code of the event handler fires an exceptions telling:

function handleFieldsDDLEvent(e) {
    var elementId = (e.target || e.srcElement).id;
    var IdArray = elementId.Split('_');
    var ControlId = "Control_"+IdArray[1].toString();

    if (IdArray[1] != "") {
        var FieldsDDL = document.getElementById("<%="+ControlId +".ClientID%>"); 
        // error CS1026: ) expected 

    ValueTxtBx.style.display = "none";
    }
}

Answer 1

In your javascript you have

var FieldsDDL = document.getElementById("<%="+ControlId +".ClientID%>");

The <%= ... %> parts are rendered on the server so it cannot be done this way in javascript.