Add webassembly-js-api for *_bg.d.ts.

[konkers]

Per #1040, import 'webassembly-js-api' is needed for WebAssembly.Memory.

[alexcrichton]

Thanks for the PR!

This inspired me to write some tests we can run on CI to ensure that this doesn't regress. In making that though I'm wondering if this is necessary? There it looks like just depending on @types/webassembly-js-api is enough to pacity the TypeScript compiler, but I'm curious if perhaps there's a common way to use TypeScript or configure it which does require this? (I'm not too familiar with TypeScript myself)

[konkers]

Ooh Typescript tests. Nice.

So, I'm not super familiar with with TS either. I looked around a bit. Essentially you're asking the TS compiler to introduce something into the global scope automatically. As far as I can tell, that's not a common thing to do.

[alexcrichton]

I agree yeah it's nonstandard and in general a bad idea, but for this case specifically WebAssembly is like String and Array where it's ambiently available in JS (part of the JS spec) and doesn't typically need an import. For that I think the import shouldn't be necessary because the JS types are already in scope and don't need imports

[Pauan]

I have a lot of experience with TypeScript.

Yeah, this needs to be added to the TypeScript compiler. They already do that for ES6 + DOM APIs. That's the standard way that TypeScript handles globals.

They have a tracking issue here: microsoft/TypeScript#29747

[alexcrichton]

Thanks for the reference and comment @Pauan! Sounds like we should close this for now but recommend depending on @types/webassembly-js-api in the meantim?

[Pauan]

Yes, installing @types/webassembly-js-api should be enough for now (TypeScript automatically loads type definitions from the @types namespace).

If that issue takes too long to fix, we can gently ping the TypeScript team.

[alexcrichton]

Sounds good to me!

@konkers would you be interested in perhaps sending a PR to update our documentation for using TypeScript to indicate this?

[konkers]

Odd! I though I tried with just@types/webassembly-js-api installed. Guess not. I reverted my patch and it's all working now. Thanks for the pointers @Pauan!

[konkers]

Yeah, I'll send a PR for a doc update.

[konkers]

I'm thinking that adding an example using typescript with callouts about @types/webassembly-js-api and the necessary webpack configs would be best. Thoughts?

[alexcrichton]

@konkers an example sounds like a great idea to me!

[abau]

Yes, installing @types/webassembly-js-api should be enough for now

Just for the record, apparently one has to install @types/webassembly-js-api@0.0.3 since installing the latest version fails due to:

$ npm install --save @types/webassembly-js-api
npm WARN deprecated @types/webassembly-js-api@2.0.0: This is a stub types definition. webassembly-js-api provides its own type definitions, so you do not need this installed.
npm ERR! code E404
npm ERR! 404 Not Found - GET https://registry.npmjs.org/webassembly-js-api - Not found
npm ERR! 404 
npm ERR! 404  'webassembly-js-api@*' is not in the npm registry.
npm ERR! 404 You should bug the author to publish it (or use the name yourself!)
npm ERR! 404 It was specified as a dependency of '@types/webassembly-js-api'
npm ERR! 404 
npm ERR! 404 Note that you can also install from a
npm ERR! 404 tarball, folder, http url, or git url.