App extension typescript support

It would be nice if quasar would support app extensions written in typescript.

At least the following should be considered:

• Make quasar create my-ext --kit app-extension ask the user if he wants to write his AE in typescript, and if so, scaffold all required typescript tools and code into the AE.
• If typescript is used, JS should still be supported. For this the code should probably be transpiled. For files in the templates folder there should probably be a way to transpile them to JS after rendering them (a better but more complicated approach than https://github.com/quasarframework/quasar/pull/7297).
• Since quasar handles the install/index/prompts API files, there should be a way to determine if they are written in typescript and handled accordingly.

[stefanvanherwijnen]

Alright, thanks. I’ll migrate things to the ui kit, but the problem with app-extension (boot and render files) written in TS stays the same. They are also tightly coupled with the Quasar project itself (e.g. the AE might need axios which is imported from a boot file), which are non-existent when developing the AE. In JS I worked around it by just assuming it is available after installing, but typescript does not like assumptions. I’ve noticed Vue’s provide and inject functions which might help, but I haven’t looked into it yet.

So:

• Move all UI components to the ui folder
• Find a way to integrate TS boot and render files into Quasar with backwards compatibility.

[stefanvanherwijnen]

I think with the correct Rollup config and plugins it will only require some minor changes to Quasar’s AE handling to support Typescript for app extensions.

The main problem is that for some reason the official rollup Typescript plugin does not work, but rollup-plugin-typescript2 does. However, rollup-plugin-typescript2 only compiles to esnext which is not supported by Webpack 4 (atleast optional chaining operators aren’t) so Quasar will not build.

Once v2 is stable I’ll try to get everything to work and create a PR.

Edit: Actually, Quasar can also import the source .ts files directly so changing main in package.json to the src folder instead of dist seems to work for an app extension.