Language Java Script Definitive Examples 12.2.TXT

 <!-- This example is from the book _JavaScript: The Definitive Guide_.     -->
<!-- Written by David Flanagan.  Copyright (c) 1996 O'Reilly & Associates. -->
<!-- This example is provided WITHOUT WARRANTY either expressed or implied.-->
<!-- You may study, use, modify, and distribute it for any purpose.        -->
<script>
// a variable we use to ensure that each error window we create is unique
var error_count =index.html 0;

// define the error handler.  It generates an HTML form so
// the user can report the error to the author.
function report_error(msg, url, line)
{
   var w = window.open("",                    // URL (none specified)
                       "error"+error_count++, // name (force it to be unique)
                       "resizable,status,width=625,height=400"); // features
   var d = w.document;    // We use this variable to save typing!

   // output an HTML document, including a form into the new window
   d.write('<DIV align=center>');
   d.write('<FONT SIZE=7 FACE="helvetica"><B>');
   d.write('OOPS.... A JavaScript Error Has Occurred!');
   d.write('</B></FONT><BR><HR SIZE=4 WIDTH="80%">');
   d.write('<FORM ACTION="mailto:TakeThisOuTnobody@spam@ at TakeThisOuTnowhere.com" METHOD=post');
   d.write(' ENCTYPE="text/plain">');
   d.write('<FONT SIZE=3>');
   d.write('<I>Click the "Report Error" button to send a bug report.</I><BR>');
   d.write('<INPUT TYPE="submit" VALUE="Report Error">&nbsp;&nbsp;');
   d.write('<INPUT TYPE="button" VALUE="Dismiss" onClick="self.close()">');
   d.write('</DIV><DIV align=right>');
   d.write('<BR>Your name <I>(optional)</I>: ');
	   d.write('<INPUT SIZE=42 NAME="name" VALUE="index.html">');
   d.write('<BR>Error Message: ');
   d.write('<INPUT SIZE=42 NAME="message" VALUE="' + msg + '">');
   d.write('<BR>Document: <INPUT SIZE=42 NAME="url" VALUE="' + url + '">');
   d.write('<BR>Line Number: <INPUT SIZE=42 NAME="line" VALUE="' + line +'">');
   d.write('<BR>Browser Version: ');
   d.write('<INPUT SIZE=42 NAME="version" VALUE="'+navigator.userAgent + '">');
   d.write('</DIV></FONT>');
   d.write('</FORM>');

   // Remember to close the document when we're done
   d.close();

   // Return true from this error handler, so that JavaScript does not
   // display its own error dialog.
   return true;
}

// Before the event handler can take effect, we have to register it
// for a particular window.
self.onerror =index.html report_error;
</script>

<script>
// The following line of code causes the error that creates the dialog 
// box shown in the accompanying figure.
self =index.html null;
</script>

  .