ES6 doesn't need opt-in

Gavin Barraclough barraclough at
Sat Jan 7 20:00:49 PST 2012

On Jan 7, 2012, at 2:22 PM, Claus Reinke wrote:

> Could you please clarify for me: if I get a single-file codebase,
> say jquery's 6k or so lines, will I have to scan the whole file for
> ES6-only features before I can even tell whether to apply ES6
> or ES5 semantics? And will this problem increase by one level
> with every future version of ES?
> Btw, I'm really uncomfortable with implicit feature tracking -
> it works ok for people who follow all the relevant mailinglist
> discussions and spec versions, but it leaves in the dark all those
> who "just code in JS" and enter a situation where their code base
> might have to be interpreted according to any of a number of
> specs (most JS coders do not even read one version of the spec,
> but rely on blogs and books, which will equally show no explicit
> in-source sign of what spec version their examples refer to and
> whether they are out of date).

I share these concerns.

Would the implicit opt-in proposal not mean that any programmer wanting to pick up JavaScript would need to learn the history of when different syntactic constructs came into the language specification in order to understand the semantics that a given script would be evaluated with?


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