Support ES6 modules (import+export declarations)

[cvrebert]

Refs #10. Esprima harmony already supports this.

[mlegenhausen]

+1

[nzakas]

ES6 progress is being tracked here: #10

[nzakas]

Oops, hit enter too soon. We will be adding each ES6 feature from Esprima piece by piece. Module will likely be last unless someone submits a PR.

[cvrebert]

Well, there's not even a bullet point for it in #10's checklist currently.

[nzakas]

Thanks, I just added it.

[caridy]

@nzakas I can probably take care of the modules grammar as I did for esprima a while ago.

[Flickdm]

[rjhilgefort]

👍

[rosshadden]

👍

[cvrebert]

😍

[nzakas]

@caridy awesome, we'd appreciate the contribution.

[caridy]

ok, I got a chance to put some time on this last night, and a questions arise:

In esprima, we introduced {sourceType: "module"}, which defines extra.isModule flag to signal to esprima that is should enforce strict mode, and should enable export/import declarations.

In espree, it seems that extra.ecmaFeatures.<something> will be the way to switch modules on. The problem is that enabling modules implies enabling other features as per the modules' grammar, e.g.: import let foo = 1;, which requires blockBindings to be available. Is there a provision to define dependencies between features? My proposal will be to add a provision similar to {sourceType: "module"}, which will flip multiple features under extra.ecmaFeatures, in this case, modules and blockBindings, and eventually classes.

[nzakas]

I think having sourceType: "module" is the right choice, both for Esprima compatibility and also because I don't like the idea of ecmaFeatures having dependencies on one another.

So +1 to your proposal.

[MoOx]

Interested too by import/export support in espree :)

[naholyr]

👍

[jozanza]

👍 This is awesome. When can we expect it to get published to npm?

[nzakas]

When the work has been done. :)

I appreciate everyone's enthusiasm, but there's no need for additional +1ing. We're doing our best to get this done and this issue will be closed when the work is complete.

[naholyr]

You're awesome <3

[ai]

Does eslint-babel can help in this issue?

[douglasduteil]

+1

[kentcdodds]

@ai, eslint-babel doesn't support it properly either. Given:

import foo as 'foo';

foo.bar();

currently results in:

3:1  error  'foo' is not defined                              no-undef