extension modules

Brendan Eich brendan at mozilla.com
Tue Jun 23 14:38:11 PDT 2009

On Jun 23, 2009, at 1:21 PM, kevin curtis wrote:

>> At some point we might have ESn remove
>> ancient cruft so the horizontal arrows might stop pointing rightward.
> A strong +1 for doing this in ES6. IMO ES5 gives developers a strong
> backward compatible cross browser foundation for the short/medium
> term. Thus, ES6 can risk a bit of backward compatibility - not sure
> how the wider ES community feels.

That's not how compatibility works. We don't have an "ES5" engine and  
a separate "ES6" engine, nor do many (most I think) other browser  
vendors. With a single engine, we do not want too many runtime version  
tests (ideally, zero) apart from strict mode.

So the way a future ESn might break compatibility would involve the  
web moving away from the deprecated feature first. Examples we've  
discussed recently include the never-standardized foo.arguments and  
foo.caller (also the now IE-only arguments.caller) properties.


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