Subj : Re: Enumeration of extended properties of Array and Object prototypes
To   : Chris Zumbrunn <chris@deployzone.com>
From : Brendan Eich <brendan@meer.net>
Date : Sun Mar 21 2004 11:14 am

Chris Zumbrunn wrote:

> Of course, I meant "any application that uses for/in loops to iterate 
> through objects that serve as collections".

Besides hasOwnProperty, for Arrays you could enumerate from 0 to 
length-1.  But perhaps you want non-indexed properties defined by users 
on the instance to be enumerated (but again, not prototype user-defined 
properties).  That suggests using hasOwnProperty.

Ideally, there'd be a direct (no prototype enumeration) for..in variant, 
but I kept the original language very simple, and no one has thought to 
add such a construct in ECMA.

/be

.