How to detect unused variables in Typescript?

Question

Is there a way to detect unused variables in Typescript (something like ESLint in Javascript)?

Taytay · Accepted Answer · 2016-10-21T19:09:48.650

59

As of version 2.0, Typescript has built-in support for detecting unused local variables and parameters. The compiler flags are as follows:

   --noUnusedLocals                    Report Errors on Unused Locals.
   --noUnusedParameters                Report Errors on Unused Parameters.

edited Oct 21 '16 at 19:09

answered Jul 14 '16 at 21:10

Taytay

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16

What if you just want these as warnings? – Izhaki Sep 07 '17 at 11:52
1

In that case you could use ESLint and configure it to emit a warning instead of an error for this rule: https://eslint.org/docs/rules/no-unused-vars – Taytay May 24 '20 at 17:24
I didn't get How should I use the above comments. I am sorry I am new to this Angular stuff. can you help me to say how to use this comments ? – Raghu Krishnan R Aug 07 '20 at 15:37

score 18 · Answer 2 · answered Feb 26 '19 at 20:01

18

You can also detect unused variables in Typescript by updating the project’s tsconfig.json file to include noUnusedLocals and noUnusedParameters:

{
  "compilerOptions": {
    "noUnusedLocals": true,
    "noUnusedParameters": true
  }
}

answered Feb 26 '19 at 20:01

Beau Smith

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score 12 · Answer 3 · edited May 08 '19 at 23:33

12

You can use TSLint instead.

https://palantir.github.io/tslint/

There's a rule for that: https://palantir.github.io/tslint/rules/no-unused-variable/

Edit:

Although this works, if you are using TypeScript 2 +, the compiler flags/options mentioned in the other answers.

edited May 08 '19 at 23:33

Beau Smith

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answered May 25 '16 at 15:21

thitemple

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This is the way forward! – gdgr May 25 '16 at 15:22
It is, as I said after editing the response, you should use the solution proposed by @Taytay – thitemple Mar 10 '18 at 13:36
In light of the community's desire to keep this rule, it has been *UNDEPRECATED*! woop woop! https://github.com/palantir/tslint/pull/2256 – protoEvangelion Nov 10 '18 at 23:25
It has been deprecated again unfortunately – Craig Wayne Sep 08 '20 at 11:41

How to detect unused variables in Typescript?

3 Answers3