Add TypeScript linting support

[Timer]

We should lint TypeScript files and try to approximate to match our ESLint configuration as close as possible.

TSLint rules we want:

• no-namespace: enforce usage of ES Modules / disallow deprecated behavior
• no-duplicate-super: prevent runtime error
• no-duplicate-switch-case
• no-duplicate-variable: prevent redeclare of var
• no-invalid-template-strings
• no-invalid-this
• triple-equals
• use-isnan
• react hooks plugin
• match eslint config closely
• restrictedGlobals

maybe:

• no-switch-case-fall-through
• no-implicit-dependencies

[copiali]

+1 Really need support for tslint.....

[Vinnl]

I think TSLint also has a few that can catch errors that cannot be supported by ESLint, such as no-floating-promises - wouldn't it be a good idea to catch as many potential errors as possible, even if they diverge from the ESLint configuration?

[ianschmitz]

TSLint React Hooks: palantir/tslint-react#186

[christianchown]

@copiali for now, you can add linting manually:

• yarn add tslint tslint-react tslint-whatever-else-you-use
• tslint.json in your root
• "lint": "tslint -c tslint.json src/**/*.{ts,tsx}" in your package.json scripts (I also add --fix --format verbose)

and then yarn lint

[mrmckeb]

There was a discussion around tslint vs typescript-eslint-parser here. I personally prefer eslint as it has many more features, but from using typescript-eslint-parser I fear it isn't ready.

If we could get this in, with close to parity on the eslint config, I think it'd be a great solution.

Can I help with this effort?

[ianschmitz]

@mrmckeb we're well under way adding support for this. It will be part of the 3.0 release.

See https://github.com/ianschmitz/create-react-app/tree/tslint and give it a try!

[mrmckeb]

I'll take a look, thanks @ianschmitz. In the interim we'll use the WIP version.