Javascript error: function XXXX() not defined

Question

I added a javascript function in a page

 <head>
    <script type=text/javascript>
        function show_Alert(error)
        {
           alert(error);
         }
    </script>
</head>

and on button click I am doing this

Protected void btn_Click(object o,Eventargs e)
{
    StringBuilder str = new StringBuilder();
    str.AppendLine("show_Alert('XYZ error')");
    ClientScript.RegisterStartupScript(GetType(),"Alert",str.ToString(),true);
}

But it throws JS error show_Alert is not defined :(

Any Idea, what is wrong here??

Thanx

Sorry That was not a issue, I am editing question

BreakHead
– BreakHead

2010-12-23 14:07:47 +00:00
Commented Dec 23, 2010 at 14:07 — BreakHead
– BreakHead, Commented Dec 23, 2010 at 14:07

SLaks · Accepted Answer · 2010-12-23 14:06:08Z

4

Your script tag is wrong.
Change it to

<script type="text/javascript">

However, I don't think that's the issue.
I suspect that RegisterStartupScript is emitting its <script> block before the one with your function, so that it ends up calling the function before it exists.
Check where each <script> is in the rendered source.

answered Dec 23, 2010 at 14:06

SLaks

891k182 gold badges1.9k silver badges2k bronze badges

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

2 Comments

BreakHead Over a year ago

SLaks RegisterStartupScript creates new <script> block and not in a head. I think that is a problem.

SLaks Over a year ago

If it's after the <head>, it shouldn't be a problem. Put a normal alert() call at the beginning of each script and check what order they're alerted

Nick Craver · Accepted Answer · 2010-12-23 14:07:05Z

2

Make sure your <script> element is valid, like this:

<head>
  <script type="text/javascript">
    function show_Alert(error)
    {
      alert(error);
    }
  </script>
</head>

If it's not well formed, or the type is unrecognized (your case has both) then the script inside will be ignored, since the browser doesn't know how to handle it.

answered Dec 23, 2010 at 14:07

Nick Craver

631k138 gold badges1.3k silver badges1.2k bronze badges

Comments

Darin Dimitrov · Accepted Answer · 2010-12-23 14:22:17Z

0

Here's an example:

<%@ Page Language="C#" %>
<script type="text/C#" runat="server">
    protected void BtnClick(object sender, EventArgs e)
    {
        var str = "XYZ Error";
        var script = new StringBuilder();
        script.AppendFormat("showAlert('{0}');",
            HttpUtility.JavaScriptStringEncode(str)
        );
        ClientScript.RegisterStartupScript(GetType(), "alert", script.ToString(), true);
    }
</script>
<!DOCTYPE html>
<html>
<head>
    <title></title>
    <script type="text/javascript">
        function showAlert(error) {
            alert(error);
        }    
    </script>
</head>
<body>
    <form id="Form1" runat="server">
        <asp:LinkButton ID="Btn" runat="server" Text="Click me" OnClick="BtnClick" />
    </form>
</body>
</html>

A very important thing to pay attention to is to properly encode the string you are passing to the showAlert function. Notice that it is encoded:

script.AppendFormat("showAlert('{0}');",
    HttpUtility.JavaScriptStringEncode(str)
);

If you don't encode it and the string contains some special characters like ' for instance, your script will break.

answered Dec 23, 2010 at 14:22

Darin Dimitrov

1.0m276 gold badges3.3k silver badges3k bronze badges

2 Comments

BreakHead Over a year ago

HttpUtility doesn't have any option of JavaScriptStringEncode :(

Darin Dimitrov Over a year ago

@BreakHead, yeah that's .NET 4.0. You could use new JavaScriptSerializer().Serialize(str) as an equivalent in older versions of .NET.

Collectives™ on Stack Overflow

Javascript error: function XXXX() not defined

3 Answers 3

2 Comments

Comments

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

2 Comments

Comments

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related