TypeScript linter warning: no-unused-variable is deprecated; but I'm not using this config

Question

Today I see this warning in a project being refreshed after 3 months.

no-unused-variable is deprecated. Since TypeScript 2.9. Please use the built-in compiler checks instead.

But my tsconfig.json does not seem to use this.

{
  "compilerOptions": {
    "lib": ["es6"],
    "module": "commonjs",
    "noImplicitReturns": true,
    "outDir": "lib",
    "sourceMap": true,
    "target": "es6",
    "allowJs" : true
  },
  "compileOnSave": true,
  "include": [
    "src"
  ]
}

Probably it's a config implicit in any of the previous configs.

Could you point me to what to do to fix it?

If usefull

$ node -v
v10.3.0
$ npm -v
6.1.0

And these are devDependencies relates to type script in my package.json

"devDependencies": {
    ...
    "tslint": "^5.11.0",
    "typescript": "^2.9.1"
    ...
  },

It's a TSLint warning. Look in the `tslint.json` file for the rule configurations. — cartant, Jul 31 '18 at 20:08

score 69 · Accepted Answer · edited Jan 02 '20 at 09:44

69

no-unused-variable is deprecated. Since TypeScript 2.9. Please use the built-in compiler checks instead.

Remove deprecated no-unused-variable from your or dependency tslint.json file.
Specify the following compiler options in your tsconfig.json file.

"compilerOptions": {
  "noUnusedLocals": true,                /* Report errors on unused locals. */
  "noUnusedParameters": true             /* Report errors on unused parameters. */
}

edited Jan 02 '20 at 09:44

Appulus

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answered Dec 05 '19 at 10:43

am0wa

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Tested. Best answer. – Ali Abdulaal Apr 15 '21 at 01:56
how to use this rule inline? that my question. – Hari Kishore Jun 23 '21 at 08:36
thank you! I was confused as I thought tsc compilation reads eslint rules, and I had no-unused-vars turned off there, but it turns out that I need this in tsconfig – Arjun Patel Feb 04 '23 at 18:07

score 37 · Answer 2 · edited Feb 07 '20 at 12:34

37

As it says, tslint deprecated that rule (more info here https://github.com/palantir/tslint/pull/3919)

Check your tslint.json, and remove the rule and the warning should disappear.

edited Feb 07 '20 at 12:34

BuZZ-dEE

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answered Jul 31 '18 at 20:10

Diego Pedro

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Thanks. I checked `tsconfig.json` _but not checked_ `tslint.json`. – realtebo Jul 31 '18 at 22:02
28

But what does `Please use the built-in compiler checks instead.` mean? – Thomas Ebert Sep 27 '18 at 09:41
38

@ThomasEbert this means adding `noUnusedLocals`/`noUnusedParameters` to `compilerOptions` in `tsconfig.json`. – crackmigg Nov 23 '18 at 15:36
2

@migg has the real answer here. Don't just remove the rule without adding this. – Leonardo Chaia Oct 28 '19 at 14:55
4

This doesn't seem like it should be deprecated, though, as `noUnusedLocals` does NOT catch unused imports, while `no-unused-variable` DOES catch unused imports. – Big Money Oct 06 '20 at 00:34

score 9 · Answer 3 · answered Dec 02 '19 at 11:03

9

Not only support for no-unused-variable rule, but the whole TSLint has been deprecated in favor of typescript-eslint.

Consider migration to new linter.

answered Dec 02 '19 at 11:03

Islam Murtazaev

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Note that at the time of writing of this comment, Angular is still uses TSLint by default. The migration for Angular is still in progress. So Angular users might still want to stick TSlint for a short while until the Angular team is done with migrating. – Edwin Stoteler Nov 12 '20 at 11:37

TypeScript linter warning: no-unused-variable is deprecated; but I'm not using this config

3 Answers3

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