Add import() support

[chicoxyzzy]

It should replace System.import method https://github.com/tc39/proposal-dynamic-import

The proposal can possibly move to stage 3 next week

[cramforce]

Happy to take a PR :)

On Nov 27, 2016 9:31 AM, "Sergey Rubanov" notifications@github.com wrote:

It should replace System.import method https://github.com/tc39/proposal-dynamic-import

The proposal can possibly move to stage 3 next week https://github.com/tc39/agendas/blob/master/2016/11.md

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[chicoxyzzy]

It is on stage 3 now

[chicoxyzzy]

import is reserved words so dynamic imports can't be polyfilled. They should be transpiled. So we probably need Babel plugin first

[chicoxyzzy]

There is https://github.com/babel/babel/tree/master/packages/babel-plugin-syntax-dynamic-import so I suppose we can use custom plugin to transpile it to current System.import. @cramforce are you ok with that?

[cramforce]

Definitely would need to be polyfilled using rewriting of files. The main thing is resolving the module identifier to a bundle URL.

On Thu, Dec 1, 2016 at 2:57 PM, Sergey Rubanov notifications@github.com wrote:

import is reserved words so dynamic imports can't be polyfilled

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[cramforce]

Just saw the second comment. My email was delayed.

Yeah, you can insert that path in here: https://github.com/cramforce/splittable/blob/master/splittable.js#L223

And then look for System.import in the evil regex below and that might work!

[chicoxyzzy]

I just created babel plugin which replaces import() with System.import(). I think it could be added to line you mentioned but tests look complicated. I didn't figure out how to add tests for import()

[cramforce]

Cool. I can take it from there. Does the plugin do nothing except s/import/System.import. One very useful feature would be a hook to control rewriting of the module argument (Going from module identifier to URL).

[chicoxyzzy]

Yes, it replaces dynamic imports with System.imports but not just s/import/System.import because we should replace only import calls, not static imports.

One very useful feature would be a hook to control rewriting of the module argument (Going from module identifier to URL).

Not sure if this logic should be in babel plugin. System.import needs this too, right?

[cramforce]

It cannot be correctly done at runtime. The nice thing about import is that it resolves a relative module name. A regular function call cannot know what '../foo' means, because it doesn't know about filenames anymore.

[chicoxyzzy]

That's true. Can you explain what changes do you want from transformer?

[cramforce]

@chicoxyzzy It would either be configurable or something predictable. E.g. if the resulting path was always a relative path from the project root instead of the current file, then everything else could be done at runtime.

[chicoxyzzy]

ok I'll try to add an option for import specifier to be exactly StringLiteral and a relative path.