Add "deno lint" subcommand

[ry]

For linting files.

Probably should be implemented similar to how we've done --fmt ... that is get eslint into deno_std, and then load from URL in core.

[zekth]

eslint and those plugins:

• @typescript-eslint/eslint-plugin
• @typescript-eslint/parser
• eslint-config-prettier

So in term of updates, Deno will update on major releases of Typescript / eslint? To stay as tied as the LTS version of those dependencies.

[kitsonk]

Also, eslint needs access to TypeScript to perform its duties, currently the Deno runtime does not give access to TypeScript, it only exists in the compiler.

[tunnckoCore]

Agree with @zekth, plus probably eslint-plugin-prettier.

Also believe that if/when this is done, we can allow deno fmt to actually also use the eslint (and also the autofix).

I almost always have autofix enabled, both when using through terminal and in vscode. So it picks the eslint config AND the prettier config to automatically fix and format everything. Great consistency.

It doesn't even matter what I write and how I write it. I'm always a 1ms away from Ctrl+S or on pre-commit. I don't need to care or even know what tha heck I'm doing, the macine/tool/system is smart enough to correct me, help me and guide me if I'm wrong.

[tunnckoCore]

The deno fmt can be just deno lint with just try/catch and always exit with 0 code.

side thoughts:
I have pretty robust config using Airbnb, typescript-eslint, Prettier (the plugin & config), React, plugin-import, plugin-unicorn, plugin-promise, plugin-node, config XO, XO-typescript. With their recommended presets and few customizations (with described reasons as comments) for the modern day and age, and more cleaner & sane code. And I have to tell you that I'm using this to that extent for around 1-2 years (Airbnb user for 3+ years), and it's insanely well.

I'm going to market it and promote it more, probably in the beginning of next year, because I really think it at least worth reviews and discussions.

All this should be build into "the language"/runtime, then easily write a thin wrapper arond the main CLI binary and voila you have editor integrations. From there, you have unlimited powered and amazing DX.

[kt3k]

Note about implementation:

https://github.com/mysticatea/typescript-eslint-demo

• This project runs @typescript-eslint on browser
• demo: https://bit.ly/2reVCoh

ESLint doesn't support browser officially, but one of the eslint core contributers, @mysticatea (Toru Nagashima), maintains browser version of eslint engine at https://github.com/mysticatea/eslint4b . The above demo uses this module as eslint engine. Probably we can reuse this module in Deno and are able to perform eslint checks.

[tunnckoCore]

I don't think we need "browser support"-ed eslint. Deno is not run in browser, but in server-side as cli.

The only problem might be the size of Deno, which may increase drastically. For some time I'm thinking to bundle ESLint with @zeit/ncc to see what will be the size.

[brandonkal]

This could be useful without eslint to replace tsc --noEmit.

[trevordmiller]

I would suggest having the linting setup include preventing errors out of the box; perhaps extending eslint:recommended (which is common problems only), something like:

{
    "parserOptions": {
      "ecmaVersion": X
    },
    "extends": [
      "eslint:recommended"
    ]
}

[nayeemrmn]

Is there any update on the plan for deno lint, considering std subcommands aren't a thing anymore?

[bartlomieju]

Is there any update on the plan for deno lint, considering std subcommands aren't a thing anymore?

@nayeemrmn most likely it will be implemented in Rust using swc.

[tunnckoCore]

@bartlomieju how? swc isn't for linting.

[axetroy]

Here I give my personal opinion:

Do not allow the user to customize linter's rulers

The community has spent too much time arguing which style is better

No need to waste more time on things like this

The user has only one choice, with use or not use

keeping the style consistent is important

Otherwise, in the future, tools like eslint/tslint/denolint will be born

and users are confused with "Which one should I choose?"