ES6 doesn't need opt-in

Axel Rauschmayer axel at
Wed Jan 4 08:41:35 PST 2012

On Jan 4, 2012, at 13:23 , Andreas Rossberg wrote:

> Considering all that, I can't help feeling that having a separate mode
> is cleaner, simpler, and easier to use. I think it also has more
> potential for providing a robust foundation for future evolution of
> the language.

Taking a step back from modes: What will ES6 support for legacy browsers look like?

- Wouldn’t you know per piece of code/file whether it is ES5 or ES6? And make that decision (all in or all out) per browser? I still don’t completely understand why/when it would be a mixed affair. I would write minimal setup code inline and then load a module as quickly as possible.

- One possibility: several versions of each file: ES3, ES5, ES6. Are there ideas for how we could either statically keep the versions and let each browser load the appropriate one or how we could dynamically compile (either server-side or client-side, possibly including caching)? This multi-version scheme could even be applied to (the JS code embedded in) HTML files.


Dr. Axel Rauschmayer
axel at


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