Subj : Re: Constructor function cleanly failing
To   : netscape.public.mozilla.jseng
From : Shanti Rao
Date : Mon Jan 10 2005 09:49 am

Matthew Mondor wrote:

> Hi all,
> 
> I was wondering if it is possible for a constructor function for a class
> to return with an error to notify the script, although not causing
> script execution to stop?  Must object creation with "new" always
> succeed for a script to continue in ECMAScript?
> 

You can trap exceptions in the calling code, like

var a;
try {
  a = new Foo()
} catch(x) {}

The exception (x) can have extra information passed from your constructor.

JS_SetPendingException(cx,STRING_TO_JSVAL(JS_NewStringCopyZ(cx,"Error 
description")));
*rval = OBJECT_TO_JSVAL(NULL);
return JS_FALSE;

.