RFC: TypeScript plugin

[yyx990803]

The TypeScript plugin now has a preliminary implementation here with:

• ts-loader
• fork-ts-checker-webpack-plugin
• tslint

TODOs

• Make the npm run lint script work with *.vue files
• Ensure compatibility with other plugins (PWA and test plugins)
• Offer options to use TS alongside Babel

Trying it Out

npm install -g @vue/cli
vue create ts-project
# select manual mode, pick TypeScript

For background on how plugins work in the new vue-cli, see here

Feedback welcome!

/cc @DanielRosenwasser @ktsn @HerringtonDarkholme @octref @kaorun343 @igogrek @prograhammer @Toilal

[igogrek]

Looks great, but wasn't able to run due to the same problem as in this thread #717.
Had to use node ..\@vue\cli\bin\vue create test-app, but yarn serve still gives me:
'vue-cli-service' is not recognized as an internal or external command

Minor note for the code:
App.vue has import like this import HelloWorld from './components/HelloWorld.vue';
But Home.vue has import HelloWorld from '@/components/HelloWorld.vue';
Which is inconsistent.
Also note that I couldn't tweak any of my IDE (WebStorm/VSCode) to properly understand @ alias.
There are some ways to ignore this as error, but it doesn't seem to work with refactorings (which is why I don't personally use it at all and still prefer longer ../../paths even for large projects).

[zeratulmdq]

Awesome work, I'll take a look tomorrow. Been waiting for this!

[zeratulmdq]

I gotta say this is the first time I use Vue with TS (been using TS with Angular for a while). I read this guide and the official TS guide so most of what I'm about to say might be just my lack of experience.

I set up the project and everything is working. I still need to fully understand the way this plugin system is gonna work. It wasn't complicated to set up everything but I would have expected a tslint/tsconfig file out of the box and the addition of "@vue/cli-plugin-typescript": "3.0.0-alpha.1", to package.json. I guess I must be missing something (some command maybe to tell the project I wanna use TS).

Regarding TS itself, I understand Vue converts properties inside the data object into getters/setters so this might be kind of complicated to acomplish without modifying internal things but I would expect something like this to throw:

import {Person} from '../models/person';

interface Data {
  msg: string;
  people: Person[];
}

export default {
  name: 'HelloWorld',
  data(): Data {
    return {
      msg: 'Welcome!',
      people: []
    }
  },
  created() {
    this.people = someService.randomNumber();
  }
}
</script>

I mean, I'm typing data() but that's just for the initial rendering. Inside the created hook I'm assigning a number to a previously typed data property and it will work. Is there a workaround for that?

BTW, as I always say, awesome work.

[igogrek]

@zeratulmdq
Good point, but until typings are improved for such cases the only good way to proceed is to use vue-class-component (there's an option already).
This way you can declare msg and people as class properties and error will be thrown.

[Toilal]

Use export default Vue.extend({}) for better TypeScript integration into Vanilla API (without vue-class-component). (Since Vue 2.5)

[Toilal]

I just tested generating a TypeScript project and a default project.

This is a really good base and seems really simpler to bring a custom feature into vue-cli.

Main difference from stable version is that no webpack configuration file is generated. I see two drawbacks for this choice :

• It may break some editors features.

For example, IntellijIDEA can parse webpack configuration like webpack aliases. So in IntelliJ IDEA with default template (no typescript), when I write import HelloWorld from '@/components/HelloWorld.vue', it shows a warning and the module is not resolved in the editor (=> no completion, no navigation, etc ...). With TypeScript option, it works because it relies on tsconfig.json compilerOptions.paths.

• It may be hard for a end-user that is not involved in vue-cli project to add an additional webpack plugin/loader.

[zeratulmdq]

Thanks @Toilal @igogrek I'll take a look

[yyx990803]

@Toilal you can access the webpack config as a file via node_modules/vue-cli-service/webpack.config.js

We will have a a ton of examples and recipes teaching users how to tweak the webpack config for common use cases.

[octref]

@yyx990803 Will writing plugins that use webpack-chain the main way to tweak webpack config?
Since changes made to node_modules/vue-cli-service/webpack.config.js will be lost after reinstall deps...right?

Other than that, PWA + TS seems a pretty solid setup for me. Will use it for a toy project to see how it goes and give more feedback.

[yyx990803]

Update: we have started making alpha releases! You can now directly test the new CLI by following the guide in README.

[veber-alex]

Can you add tslint-config-standard as an option when enabling TSLint?

[franxois]

Hi,
great work ! I don't know if it the right place but here is my tests

npx @vue/cli create vue-ts-test

Vue CLI v3.0.0-alpha.5
? Please pick a preset: Manually select features
? Check the features needed for your project: TS, PWA, Router, Vuex, CSS Pre-processors, Linter, Unit, E2E
? Use class-style component syntax? Yes
? Use Babel alongside TypeScript for auto-detected polyfills? No
? Pick a CSS pre-processor (PostCSS, Autoprefixer and CSS Modules are supported by default): LESS
? Pick additional lint features: 
? Pick a unit testing solution: Jest
? Pick a E2E testing solution: Cypress
? Where do you prefer placing config for Babel, PostCSS, ESLint, etc.? In dedicated config files
? Save this as a preset for future projects? No

If I run npm run serve it show errors like below but i can browse and hot reload works

ERROR in /tmp/vue-ts-test/node_modules/@types/jest/index.d.ts
18:13 Duplicate identifier 'beforeEach'.
    16 | 
    17 | declare var beforeAll: jest.Lifecycle;
  > 18 | declare var beforeEach: jest.Lifecycle;
       |             ^
    19 | declare var afterAll: jest.Lifecycle;
    20 | declare var afterEach: jest.Lifecycle;
    21 | declare var describe: jest.Describe;
 

̀npm run build fails

[yyx990803]

@franxois looks like a type conflict between Cypress and Jest. We will need explicit tsconfig.json inside test directories.

Tracked in #762

[franxois]

Hi, i just try with v3.0.0-alpha.6, it's ok now ! :)

[yyx990803]

@DanielRosenwasser I think we are more or less stable now, would love to get your feedback on this before we move to beta :)

[Toilal]

I just gave a try to the new generator (alpha 7) with all options checked (including TypeScript). It runs smoothly and is zero-conf for opening the generated project in IntelliJ.

Class component option could be available without TypeScript too.

When disabling TypeScript, I have to configure the webpack configuration file in IntelliJ (node_modules/@vue/cli-service/webpack.config.js) for @ import alias to be recognized, but then all is OK. I think custom configuration placed in vue.config.js won't be available to IntelliJ.

Maybe the mutated webpack configuration could be written to a file so the effective final configuration can be loaded by tools/editors ?

Thanks for the awesome work 👍

[yyx990803]

@Toilal that webpack file exports the dynamically resolved config that includes your custom config as well ;)

[dkulchenko]

Looks awesome!

Would it be possible to have a choice between TSLint and ESLint, even when in TypeScript mode?

I much much prefer working with ESLint even on my TypeScript Vue projects (better VSCode support, eslint-plugin-vue doesn't have a TS equivalent, etc.). Tried it both ways and I've found life to just be a lot easier with ESLint at the moment.

It's a relatively straightforward integration - it means instead of adding tslint and tslint.json, keeping eslint as normal and adding the typescript-eslint-parser and eslint-plugin-typescript npm deps, then taking eslintOptions.js from cli-plugin-eslint and changing a few options:

  extensions: ['.js', '.ts', '.vue'],
  parserOptions: {
    parser: require.resolve('typescript-eslint-parser'),
    sourceType: 'module',
  },
  plugins: ['typescript'],

Also adding the ts extension to the webpack eslint-loader test in cli-plugin-eslint, and tweaking a few enabled eslint rules, but all else should be essentially untouched.

[yyx990803]

@dkulchenko cool, I actually didn't know you can use ESLint with TypeScript before. I think that's indeed a better setup than TSLint. Will investigate in the next release.

[ajafff]

@yyx990803 @dkulchenko would you consider using a completely different linter instead?

TSLint currently doesn't support .vue files. It's unlikely that this feature will be added anytime soon as it requires a major rewrite. In addition the project seems to be abandoned by its owners. That's why I'm no longer working on it.

IIRC ESLint with typescript-eslint-parser has problems to provide correct type information because every file is checked in isolation.

I'm currently working on a replacement for TSLint that can be fully customized: https://github.com/fimbullinter/wotan
There's also a processor for vue files (similar to eslint-plugin-vue): https://github.com/fimbullinter/wotan/blob/master/packages/ve/README.md
And you can optionally use existing TSLint core rules as well as custom rules: https://github.com/fimbullinter/wotan/blob/master/packages/heimdall/README.md

[DanielRosenwasser]

@yyx990803 I will try to stress test it soon!

I think one thing that would be super high-value would be a lint rule to warn Vue+TypeScript users about computed properties, where all methods and get/set accessors need to have explicit type annotations to avoid inference problems with TypeScript (vuejs/vue#7394). Whatever linter we end up choosing, we should factor that into the starter.

[yyx990803]

@DanielRosenwasser it's possible to use either ESLint (via typescript-eslint-parser) or TSLint, but I assume the implementation of the rule would be similar. I think in the long run we'd like to standardize around ESLint because that allows linting of templates inside SFCs, and the rule you proposed could be placed in https://github.com/vuejs/vue-cli/tree/dev/packages/%40vue/eslint-config-typescript

/cc @mysticatea @michalsnik

[mysticatea]

Cool.

In fact, the combination of vue-eslint-parser and typescript-eslint-parser needs more work a bit. It needs that typescript-eslint-parser supports parseResult.visitorKeys.

Currently, I'm busy on acorn and eslint to support ES2018, but I will work on it after done.

[prograhammer]

@mysticatea @dkulchenko @yyx990803 Does the ESLint plugin support rules that use the type checker?

[yyx990803]

@prograhammer AFAIK, no. With the current setup, type checking is performed by fork-ts-checker-webpack-plugin in a separate thread, and we don't even enable type checker depending rules when using TSLint.

[prograhammer]

Ah, ok. Now I'm wondering why you wouldn't enable tslint in fork-ts-checker-webpack-plugin, but it looks like you need the ability to tslint fix files or run tslint separately from fork-ts-checker-webpack-plugin?

[prograhammer]

@yyx990803 fork-ts-checker-webpack-plugin can pass the program over (the program will read .vue files in a way that line/column positions are preserved) to tslint. You just enable the tslint flag in fork-ts-checker-webpack-plugin. What repo is generating the webpack config in this new Vue Cli setup?

[yyx990803]

@prograhammer actually, when using lintOnSave: true, tslint is done via fork-ts-checker-webpack-plugin, and I think that does work with type-checker-dependent rules.

[DanielRosenwasser]

Hey @yyx990803, since you already have support for TSLint, is there a specific place we should place the rule? I know that the respective ESLint rule should probably go in https://github.com/vuejs/eslint-plugin-vue

[yyx990803]

@DanielRosenwasser currently TSLint is handled inside the TypeScript plugin itself and we are just using tslint:recommended. We don't really have a TSLint config at the moment. Maybe put it as a custom rule in a rulesDirectory for now?

[prograhammer]

@yyx990803 @DanielRosenwasser
I personally use tslint-config-standard (set in a tslint.json), which requires the type-checker for some rules.

[do-web]

Could you please add typescript support to "vue serve MyComponent.vue" maybe with a parameter "vue serve -ts MyComponent.vue"

[DrSensor]

I also love vue serve -ts to be implemented because when I work with medium-large project that use typescript everywhere, it consume a lot of RAM 😂

[ErikAllan]

I've just tried the typescript template and everything works perfect so far, except for one thing... How do I use typescript in the service worker file? I use this setting in the vue.config.js file to include the worker:

module.exports = {
pwa: {
workboxPluginMode: 'InjectManifest',
workboxOptions: {
swSrc: 'src/sw.js',
},
},
};

I would like to replace the sw.js file with a sw.ts file, but Workbox doesn't seem to allow that. I have a lot of code inside the service worker that needs to be written in typescript...

If this is the wrong forum for this question, please redirect me :-)