Subj : Re: JavaScript behavior in Seamonkey
To   : Samuel Cheung <SCheung@Novarra.com>
From : Brendan Eich <brendan@meer.net>
Date : Sat Sep 13 2003 02:29 pm

Samuel Cheung wrote:

> Could someone please tell me why Mozilla does that? I think if Mozilla 
> looks for any matching window properpty (in this case "onload") for 
> every single variable declaration. That will be slow. So I am 
> wondering what is the reason behind this behavior?
>

There's no reason for lookup to be "slow" -- hashing is O(1).  The ECMA 
spec clearly states that var does not change a pre-existing property of 
the variable object, which is the window object at top-level in an HTML 
or similar DOM level 0 embedding.

It has worked this way since I created all this stuff in 1995, in 
Navigator 2.0.  Any IE deviation is a bug in light of compatibility with 
"Mozilla" (which has been around for a long time, even though the layout 
engine and lots of other code was rewritten in 1998).

/be

.