Subset relation (was: RE: ES3.1 Draft: 11 June 2008 version available)

Douglas Crockford douglas at
Mon Jun 16 14:07:30 PDT 2008

>The issue that was raised by the discussion quoted below was whether
>strict mode could become /looser/ as the language version goes up; could
>ES3.1 outlaw 'with' in strict mode, but ES4 allow it again?  This feels
>weird to me.

The thing that needs to be maintained is the viability of programs that are written without anticipation of the characteristics of future standards. I don't think that needs to include the strict interpretation of what the strict mode disallows. For ES3.1, strict mode indicates that the programmer wants to use a more reliable subset of the language. If ES4's objectives are different, I think it can have its own definition of strict mode.

I agree that it is weird that ES4 wants to retain with, but that in itself does not disturb the superset relationship.

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