Fun impossible Firefox JS challenge

Brendan Eich brendan at mozilla.org
Fri Apr 13 07:47:14 PDT 2012


Some time after Firefox 4, a fix went in so we match ES5:

js> fals\u0065
false
js>

/be

Wes Garland wrote:
> On 12 April 2012 15:37, Allen Wirfs-Brock <allen at wirfs-brock.com 
> <mailto:allen at wirfs-brock.com>> wrote:
>
>     Right chrome and safari log "undefined" in that case.  FF and IE9
>     syntax error out on the var declaration.
>
>
> As long as we're exploring web compat, here's a historical view of 
> SpiderMonkey behaviour --
>
> JS 1.8.5 (~ Firefox 4) treats fals\u0065 as a valid identifier that is 
> distinct from false.
> Same for JS 1.7 (~ Firefox 3)
> Same for JS 1.6 (~ Firefox 2)
> Same for JS 1.5 (ES-3)
> JS 1.4.1 does not allow unicode escapes in identifiers
>
>
>
> -- 
> Wesley W. Garland
> Director, Product Development
> PageMail, Inc.
> +1 613 542 2787 x 102 <tel:%2B1%20613%20542%202787%20x%20102>
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