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From: Robert on 10 May 2010 06:19
I have a question about the display of javascript Errors in the Firefox
Error Console. Maybe not completely on-topic, but I hope someone here
might know the answer.

The Error Console will display an error when a javascript object is
thrown (and not catched).
If this is done with the normal Error object, for example:
throw new Error("my message")
then it shows the error message and a nice link that you can use to jump
to the file and line number
where the Error object was created.

I would like to know what the exact conditions are for this link to be
displayed.
I ask this because I tried to extend the Error object in many ways to
distinguish between different
exceptions, yet still have that useful link in the Error Console.

My custom Exception object is extended in such a way that "instanceof
Error" returns true. And it contains
the fileName and lineNumber properties. Yet I still see no link.

I give some javascript to show you one method I used to extend the Error
object:

************
clone = function (object)
{
function Dummy(){};
Dummy.prototype = object;
return new Dummy();
}

extend = function (superclass, subclass)
{
subclass.prototype = clone(superclass.prototype);
subclass.prototype.constructor = subclass;
}

Exception = function(error)
{
for (var p in error)
{
this[p] = error[p];
}
}
extend(Error, Exception);
Exception.prototype.toString = function()
{
return "Exception: " + this.message + "
(filename="+this.fileName+":"+this.lineNumber+")";
}

throw new Exception(Error("my exception"));

************

Kind regards,
Robert

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