# remove-unused-vars

Remove more unused variables. Highly experimental.

> [!WARNING]
>
> There's a reason linters don't fix the unused variables, even with a flag like `--unsafe` or `--fix-dangerously`.

Modern linters can fix a lot of issues automatically, but don't always remove all unused variables and types. Even when
using `--unsafe` or `--fix-dangerously`.

Use `remove-unused-vars` to remove everything the linter finds. Then run QA and review if there's anything that might
need reverting. Needless to say, Git's your friend here!

Don't use e.g. `eslint --fix` or `biome lint --write` when piping to `remove-unused-vars`, otherwise the positions to
remove things might not match up. Use the linter first to have it remove whatever it can, then proceed with the
command(s) below.

> [!TIP]
>
> Use this with [Knip](https://knip.dev) for a cruel code crusher experience.

## Install

```sh
npm install -D remove-unused-vars
```

## Pipe JSON

Pipe the JSON-formatted output of the linter to `remove-unused-vars`

Add to `package.json#scripts`, modify the commands below and make sure to use local linter configuration.

### ESLint

```sh
eslint --rule 'no-unused-vars: error' --quiet -f json | remove-unused-vars
```

### typescript-eslint

```sh
eslint --rule 'no-unused-vars: off' --rule '@typescript-eslint/no-unused-vars: error' --quiet -f json | remove-unused-vars
```

### Biome

```sh
biome lint \
  --only correctness/noUnusedVariables \
  --only correctness/noUnusedImports \
  --only correctness/noUnusedFunctionParameters \
  --reporter json | remove-unused-vars
```

### oxlint

```sh
oxlint -A all -D 'no-unused-vars' -D '@typescript-eslint/no-unused-vars' -f json | remove-unused-vars
```

## From JSON file

Alternatively, provide a JSON file as the first argument to `remove-unused-vars`, for example:

```sh
oxlint -A all -D '@typescript-eslint/no-unused-vars' -f json > unused-vars.json
remove-unused-vars unused-vars.json
```

## Without installation

Use something like this without installing `remove-unused-vars`:

```sh
eslint -- --quiet --format json | npx -y remove-unused-vars
```