Add worker-loader dependency to support web workers

[maier49]

Type: feature

The following has been addressed in the PR:

• [ ] There is a related issue
• [ ] All code matches the style guide
• [ ] Unit or Functional tests are included in the PR

Description:

Adding this dependency would allow the use of webworkers in a dojo app using this syntax

const worker: Worker = new (require('worker-loader?name=hackerNewsWebWorker.js!./hackerNewsWebWorker'));

It works with a normal build or the dev server, and causes a separate compilation for the webworker. Dependencies can be pulled into the webworker and will be built into a separate bundle.

[kitsonk]

Awesome!

Are there any changes to authoring tests in downstream applications?

Also, we should have at least some sort of test with this as well.

[matt-gadd]

Although I have no issue with the dependency, we so far have tried to avoid inline webpack loader requires, for the same reasoning as AMD plugins.

[kitsonk]

we so far have tried to avoid inline webpack loader requires

Yeah, good point, I hadn't appreciated that. Would a better approach be an abstraction that is part of Dojo 2 (maybe core) that ensure that it worked.

Also, if we do go with an approach like this, we should still find a better way to integrate it. We can type plugins now with something like:

declare module 'worker-loader?*' {
  export = /* ... */
}

Would we not be able to create something that wrapped ES import() that we could also inject some feature detection, so the code was isomorphic on Node.js as well?

[maier49]

This feature needs further discussion to decide on the best approach. https://github.com/dojo/meta/issues/190 has been created for that purpose.