[Javascript] IE not implemented error

[Nick Fitzsimons]

On 12 Feb 2007, at 14:21:47, Flávio Gomes wrote:

> http://www.google.com/search?q=%22Error%3A+Not+Implemented%22 
> +javascript
>
> Too many to list.. but I never got it.
>
> Schalk Neethling escreveu:
>
>> Hi there everyone,
>>
>> Can anyone on the list please shed some light on the Not  
>> Implemented error thrown by IE? In general what would cause this  
>> type of error?
>>

In general, this is due to the fact that IE is built using COM  
components, COM (Component Object Model) being the technology that  
underlies much of the Windows operating system, and which is related  
to ActiveX.

It means that COM is unable to carry out some operation because it  
doesn't know how to handle what you've thrown at it. The first result  
(for me) from Flávio's Google search is to
<http://www.experts-exchange.com/Web/Web_Languages/JavaScript/ 
Q_21637722.html>
where the problem is that the code attempts to assign the result of a  
function to the onreadystatechange property of the document, rather  
than assigning a reference to the function. As the function in  
question doesn't return a value, IE gets confused by attempting to  
assign the native JScript value for "undefined" to something that  
expects a JScript function reference (which is wrapped as a COM  
object, and can be assigned to the event handler correctly).

It appears from the other search results that this is a common cause  
of this error, but I'm pretty sure I've seen it caused by other COM- 
related issues over the years.

COM is also the reason for "Interface not supported" errors which can  
crop up from time to time, particularly when doing Ajaxian things. If  
you want to know more about COM (and I'm sure you don't) then  
Microsoft's page saying it's rubbish compared to .NET is at
<http://www.microsoft.com/com/>.

Also, Eric Lippert (who was closely involved in the development of  
the MS scripting engines some years ago) has a number of articles in  
his archives at
<http://blogs.msdn.com/ericlippert/archive/tags/COM+Programming/ 
default.aspx>.

Regards,

Nick.
-- 
Nick Fitzsimons
http://www.nickfitz.co.uk/