Approach of new Object methods in ES5

Brendan Eich brendan at mozilla.com
Fri Apr 16 09:10:59 PDT 2010


On Apr 16, 2010, at 8:43 AM, Brendan Eich wrote:

> 2. Extending the language's syntax with:
>
> (a) No versioning required in the absence of new reserved  
> identifiers, since new syntax cannot break existing content.

Of course I glossed over how new syntax *could* make invalid content  
start parsing, unexpectedly. We don't generally cater to this unlikely  
case (I've never seen it).

Also, obviously existing browsers at the time new syntax is  
promulgated by one or more browsers, perhaps based only on draft specs  
but in nightly/testing builds, will cause syntax errors in old browsers.

This problem has no good solution other than server-side user-agent  
sniffing in order to ship different content to the old browsers, or  
perhaps equivalent client-side sniffing and eval usage (280 North and  
others are now compiling on the browser, not on the server side).

/be


More information about the es-discuss mailing list