Support ES Modules for Node 14 functions

[mbleigh]

Currently, it is not possible to use native ES Modules with Cloud Functions for Firebase in Node 14 due to how triggers are parsed from the code. Unfortunately, adding support is not trivial (or I would have done it when I added Node 14 support generally), but we'd like to do it in the future.

Please upvote this issue if it's important to you!

[taeold]

In addition to problems with how triggers are parsed in firebase-tools repo, the functions framework (used to load and run user-provided code in google cloud functions) doesn't seem to support ESM yet: GoogleCloudPlatform/functions-framework-nodejs#233.

[mbleigh]

@taeold good catch. Seems like even if we finished the work here we'd be blocked on that. Perhaps we should put a pin in this until work has been done in the functions framework.

[mesqueeb]

I just want to mention to all who come here to upvote:

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[larssn]

Does this affect typescript projects?

We use this tsconfig for node 14: https://github.com/tsconfig/bases/blob/master/bases/node14.json

I'm guessing it doesn't.

[mbleigh]

@larssn correct, since TypeScript with default configuration compiles down into CommonJS, it is not affected -- you can continue to use ESM in TypeScript just like you can in Node < 14.

[spicemix]

Although even in a Typescript project, the emulators refuse to use p-queue@7 for instance, leaving me using an old non-ESM version. Thanks in advance!

[Spencer-Easton]

@mbleigh Will top level await work if it compiles from TS?

[taeold]

@Spencer-Easton Yes. As long the compiled JS code that's deployed to Firebase Functions doesn't contain top level await, things will work.

[jthegedus]

@taeold

@Spencer-Easton Yes. As long the compiled JS code that's deployed to Firebase Functions doesn't contain top level await, things will work.

Do the ESLint rules generated by firebase init functions capture top-level await? If not, can we configure this rule in the template?

[taeold]

@jthegedus Good idea. We will probably want to update the template for both JS and TS to reflect ES module support in GCF.