Call a ascx Javascript function from .aspx page

Question

I have the following .ascx page(user control):

    <%@ Control Language="C#" AutoEventWireup="true" CodeFile="MultiSelectDDL.ascx.cs" Inherits="MultiSelectDDL" %>
<%@ Register Assembly="AjaxControlToolkit" Namespace="AjaxControlToolkit" TagPrefix="cc1" %>
 <link href="Styles/style.css" rel="stylesheet" type="text/css" />
<script type = "text/javascript">

    function CheckItem(checkBoxList) {
        debugger;
        var options = checkBoxList.getElementsByTagName('input');
        var arrayOfCheckBoxLabels = checkBoxList.getElementsByTagName("label");
        var s = "";

        for (i = 0; i < options.length; i++) {
            var opt = options[i];
            if (opt.checked) {
                s = s + ", " + arrayOfCheckBoxLabels[i].innerHTML;
            }
        }
        if (s.length > 0) {
            s = s.substring(2, s.length);
        }
        var TxtBox = document.getElementById("<%=txtCombo.ClientID%>");
    TxtBox.value = s;
    document.getElementById('<%=hidVal.ClientID %>').value = s;
}
</script>


<asp:TextBox ID="txtCombo" runat="server" ReadOnly="true" Width="138px" Font-Size="X-Small" CssClass="txtbox"></asp:TextBox>
<cc1:PopupControlExtender ID="PopupControlExtender111" runat="server" 
    TargetControlID="txtCombo" PopupControlID="Panel111" Position="Bottom" >
</cc1:PopupControlExtender>

<input type="hidden" name="hidVal" id="hidVal" runat="server" />

<asp:Panel ID="Panel111" runat="server" ScrollBars="Vertical" Width="142px" Height="75" BackColor="White" BorderColor="Gray" BorderWidth="1">

    <asp:CheckBoxList ID="chkList" 
        runat="server" 
        Height="75" onclick="CheckItem(this)">                                                                                                                                                                        
    </asp:CheckBoxList>

</asp:Panel>

And another normal .aspx page, in which I have placed the above user control.

What I need to do is, from a function written in .aspx.cs I want to call the Javascript written in .ascx page.

I tried:

 Page.ClientScript.RegisterStartupScript(this.GetType(),"MyFunction","CheckItem('"+ MultiSelectDDL1.ClientID +"');",true);

but it does not work. Plz help.

This should work, so you need to give more information. Are there any error messages in the console? Have you tried stepping through the code to see if it is being run. You need to give more info that "it does not work". — anothershrubery
– anothershrubery, Commented Dec 8, 2014 at 10:40
I have set a JS debugger but it never reaches there. The .aspx page contains an updatepanel, as soon as i remove it the javascript works. Why is it like that? — Jackson Lopes
– Jackson Lopes, Commented Dec 8, 2014 at 10:55

Onur Topal · Accepted Answer · 2014-12-08 11:00:44Z

2

I think the problem is you are passing a sting instead of an DOM element you should change you start up script with the below one.

Page.ClientScript.RegisterStartupScript(this.GetType(),"MyFunction","CheckItem(document.getElementById('"+ MultiSelectDDL1.ClientID +"'));",true);

answered Dec 8, 2014 at 11:00

Onur Topal

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Comments

Anant Dabhi · Accepted Answer · 2014-12-08 10:54:56Z

0

you need to pass object inseted of client id

 Page.ClientScript.RegisterStartupScript(this.GetType(),"MyFunction","CheckItem(this);",true);

answered Dec 8, 2014 at 10:54

Anant Dabhi

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1 Comment

Jackson Lopes Over a year ago

Whatever you are saying is all true, but the real problem is that as long as there is this updatepanel in my page I cannot call any JS from code behind as soon I remove it, everything works fine except certain styling issues. Why is this

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