Optional call grammar

[waldemarhorwat]

The grammar allows
a(b)?.(c)
but prohibits
a?.(b)

Is that intentional?

[jridgewell]

That's explicitly allowed.

https://github.com/tc39/proposal-optional-chaining#semantics

a?.()        // a is invoked if not null/undefined

[waldemarhorwat]

The example allows it, but the grammar in the proposal doesn't allow it.

[jridgewell]

Seems to? https://claudepache.github.io/es-optional-chaining/#prod-CallExpression

[claudepache]

@waldemarhorwat It’s a bug. The following rule is missing:

CallExpression[Yield] :
    ...
    MemberExpression[?Yield] OptionalChainingOperator Arguments[?Yield]
    ...

[rattrayalex]

This is off-topic on the question at hand, but relates to the title of the thread – where can one read about the decision to go with maybeFn?.(arg) instead of maybeFn?(arg)?

It was implied elsewhere that this debate had been had; it might be helpful to the community to have the explanation somewhere (perhaps I simply haven't found it).

[jridgewell]

where can one read about the decision to go with maybeFn?.(arg) instead of maybeFn?(arg)?

#5 (comment)

[Mouvedia]

@rattrayalex that's because there was no real debate and both issues were closed too abruptly.

[claudepache]

@waldemarhorwat The bug is fixed with the latest update. Thanks for the careful reading.