Calling Function in Codebehind of aspx from Javascript Throws Error

Question

I'm trying to call a function in the codebehind of my .aspx page once the window is fully displayed. I tried using:

    <script type="text/javascript">
    $(document).ready(function () {
        PageMethods.CheckForPageChange();
    });
</script>

And it throws the following error:

0x800a1391 - JavaScript runtime error: '$' is undefined

I was able to get window.onload to display an alert box, so I tried using it like this:

    <script type="text/javascript">
    window.onload = function () {
        PageMethods.CheckForPageChange();
    }
</script>

But it throws the error "PageMethods is undefined".

I have this inside of a "form" tag:

        <asp:ScriptManager runat="server" ID="ScriptManager1" EnablePageMethods="true"></asp:ScriptManager>

And this in my codebehind:

    [WebMethod]
    public void CheckForPageChange()
    {
        throw new NotImplementedException();
    }

Can someone please tell me what I am missing here? Any assistance is greatly appreciated!

The $ error was because you haven't loaded jQuery by the time it gets to that line. — mason
– mason, Commented Jan 20, 2017 at 21:11

Tarek Abdel Maqsoud · Accepted Answer · 2017-01-20 21:19:53Z

1

0x800a1391 - JavaScript runtime error: '$' is undefined

Make sure that the JQuery has been loaded successfully.

it throws the error "PageMethods is undefined".

1- You have to make your server side method as a static method looks like this

[WebMethod]
public static void CheckForPageChange()
{
    throw new NotImplementedException();
}

2- Call the serverside method like that

<script type="text/javascript">
function OnSuccess(response){
   //Do Stuff
}
function OnError(error){
   //Do Other Stuff
}
$(document).ready(function () {
    PageMethods.CheckForPageChange(OnSuccess, OnError);
});

3- put your script outside <asp:ScriptManager>, put it in a separate <script> tag

answered Jan 20, 2017 at 21:19

Tarek Abdel Maqsoud

581 silver badge9 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Zorken17 · Accepted Answer · 2017-01-20 21:12:42Z

0

The reason for the first error is that you do not include jQuery in your aspx page.

The next error properly is because you do not have runat="server". Try to modify your ScriptManagerlike this:

<asp:ScriptManager ID="ScriptManagerMain"
        runat="server"
        EnablePageMethods="true" 
        ScriptMode="Release" 
        LoadScriptsBeforeUI="true">
</asp:ScriptManager>

answered Jan 20, 2017 at 21:12

Zorken17

1,8861 gold badge12 silver badges16 bronze badges

1 Comment

Heretic Monkey Over a year ago

The OP has runat="server" in the ScriptManager` call. I think you mean to point out the LoadScriptsBeforeUI property.

Collectives™ on Stack Overflow

Calling Function in Codebehind of aspx from Javascript Throws Error

2 Answers 2

Comments

1 Comment

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

1 Comment

Your Answer

Sign up or log in

Post as a guest

Linked

Related