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Calling a Javascript function from codebehind button click event

Posted on 2010-08-30
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Last Modified: 2012-05-10
Do you know what could be the reason the following call to javascript alert is not working from the codebehind button click event? Here is the code and debugging even takes me to the line of code in the if block but I do not see the alert prompted:
 
protected void btnAddCurrentPart_Click(object sender, EventArgs e)
{
if (!blnCurrentPartCompatible)

{


ClientScriptManager script = Page.ClientScript;

if (!script.IsClientScriptBlockRegistered(this.GetType(), "Alert"))

{

 script.RegisterClientScriptBlock(this.GetType(), "Alert", "<script type=text/javascript>alert('Hello there')</script>");

}


return;

}

}

0
Comment
Question by:skaleem1
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14 Comments
 
LVL 30

Accepted Solution

by:
MlandaT earned 250 total points
ID: 33560530
What HTML is being generated?

Also try this:  

script.RegisterClientScriptBlock(this.GetType(), "Alert", "<script type=""text/javascript"">alert('Hello there')</script>");

Also consider:

Page.ClientScript.RegisterStartupScript(this.GetType(), "AlertScript", "alert('Hello World');", True)
0
 
LVL 38

Expert Comment

by:Tom Beck
ID: 33560541
I believe this only needs 1 argument, the script key: IsClientScriptBlockRegistered("Alert")
0
 
LVL 38

Expert Comment

by:Tom Beck
ID: 33560561
I see it also accepts 2, never mind.
0
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LVL 1

Author Comment

by:skaleem1
ID: 33560604
I even changed it to:

ClientScriptManager script = Page.ClientScript;

                if (!script.IsClientScriptBlockRegistered("Alert"))
                {

                    script.RegisterClientScriptBlock(this.GetType(), "Alert", "<script type=text/javascript>alert('Hello there')</script>");

                }

but still does not work. Please see that it is being called from a button click event. Is it an issue?
0
 
LVL 1

Author Comment

by:skaleem1
ID: 33560636
I even tried it on the OnClientClick event but still does not work:

<asp:Button ID="btnAddCurrentPart" runat="server" Text="Add Current Part" Enabled="false" OnClientClick="javascript:CheckCompatibility(); return false;" OnClick="btnAddCurrentPart_Click" />

function CheckCompatibility(CheckCompatibilityForCurrentPartInPortFolio) //
{
                       
            alert(CheckCompatibilityForCurrentPartInPortFolio);

}
0
 
LVL 55

Assisted Solution

by:Huseyin KAHRAMAN
Huseyin KAHRAMAN earned 250 total points
ID: 33560666
put this code to page_onload

ClientScriptManager script = Page.ClientScript;
if (!script.IsClientScriptBlockRegistered(this.GetType(), "Alert")) {
 script.RegisterClientScriptBlock(this.GetType(), "Alert", "<script type=text/javascript>alert('Hello there')</script>");
}
0
 
LVL 1

Author Comment

by:skaleem1
ID: 33560780
HainKurt,

I know that it works when I place this in the Page_onload event, however I have a logic in the button click event and I only want this to fire when the logic is not true, the complete code is as follows:

protected void btnAddCurrentPart_Click(object sender, EventArgs e)
        {
            RetrieveDataGateway rdg = new RetrieveDataGateway();

           
            bool blnCurrentPartCompatible = false;
            blnCurrentPartCompatible = isCurrentPartCompatibleWithPortfolio();
            if (!blnCurrentPartCompatible)
            {
               
                ClientScriptManager script = Page.ClientScript;

                if (!script.IsClientScriptBlockRegistered(this.GetType(), "Alert"))
                {

                    script.RegisterClientScriptBlock(this.GetType(), "Alert", "<script type=text/javascript>alert('Hello there')</script>");

                }

               
                return;
            }
            else
            {
                //Do whatever you want to process
            }
        }
0
 
LVL 30

Expert Comment

by:MlandaT
ID: 33560894
If you put a breakpoint... does that condition [isCurrentPartCompatibleWithPortfolio()] ever evaluate to 'false'... which would make the if work...

It certainly does not look like the problem is coming from the javascript.
0
 
LVL 1

Author Comment

by:skaleem1
ID: 33561189
Yes it does and it even steps into the if block and through the line of code that triggers the javascript without any error...
0
 
LVL 30

Expert Comment

by:MlandaT
ID: 33561314
Strange... does the javascript get emitted to the browser at all? If you View Source for the page... do you see the javascript: alert('Hello there')

Try changing this line:

     script.RegisterClientScriptBlock(this.GetType(), "Alert", "<script type=text/javascript>alert('Hello there')</script>");

TO:

     script.RegisterClientScriptBlock(this.GetType(), "Alert", "alert('Hello there');", true);
0
 
LVL 7

Expert Comment

by:urir10
ID: 33561409
can you also try this:

 ScriptManager.RegisterClientScriptBlock(btnSubmit, typeof(Button), "Saved", "alert('Hello there');", true);
0
 
LVL 55

Expert Comment

by:Huseyin KAHRAMAN
ID: 33562733
if you do this

response.write("<script type=text/javascript>alert('Hello there')</script>");

what happens ;)
0
 
LVL 1

Author Comment

by:skaleem1
ID: 33567603
Thanks for all your help however the reason was something entirely different which I found out after extensive debugging and reviewing the html view. Long story short, the button btnAddCurrentPart is part of an ajaz based update panel that was causing not to fire the client side script before the postback. What I did was to force a postback in the page load event, something like this:

btnAddCurrentPart.OnClientClick = String.Format("fnClickOK('{0}','{1}','{2}','{3}','{4}')", btnAddCurrentPart.UniqueID, "", "AddCurrentPart", _User, "");

In the fnClickOK function, I do all my client side validation before forcing a postback so that my button click event code behind executes:

 function fnClickOK(sender, e, Flag, UserLogin, IsPrivate)
       {
//Do my client side validation here:
__doPostBack(sender,e);
}

and that solved the problem. The notable thing is how the Update Panel affects the postbacks unless you design the aspx page taking into considerations with all the important options this update panel comes with...

However, because some of you pointed me to the right direction, i.e, checking the html etc., I will split the points between two of you, thanks for your help anyways.
0
 
LVL 1

Author Closing Comment

by:skaleem1
ID: 33567629
Because you pointed me to the right direction, i.e, checking the html etc., I will split the points between two of you, thanks for your help anyways.
0

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