# TypeScript: error TS6133: 'x' is declared but its value is never read.

**Code:** `TS6133: 'x' is declared but its value is never read` · **Category:** TypeScript · **Seen on:** TypeScript

`noUnusedLocals`/`noUnusedParameters` flag an unused variable, import or parameter.

## Meaning

Remove it, use it, or prefix parameters with `_` (`_req`). For imports, delete the unused import (organise imports). To relax, disable the option in tsconfig — many teams leave it to ESLint instead. Build errors in CI often come from this strict flag.

## Common causes

- Unused import/variable
- Unused function parameter (Express `req`)
- Leftover debug code
- Destructured value unused
- `noUnusedLocals` enabled

## Quick fix

1. Remove or use the identifier
2. Prefix unused parameters with `_`
3. Disable `noUnusedLocals/Parameters` or handle via ESLint

## Detailed fix by platform

### TypeScript

1. `app.get("/", (_req, res) => res.send("ok"));`

## How to diagnose

1. **Identifier** — Needed?
2. **Parameter** — _prefix?
3. **Option** — Enabled?

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Source: [WhatIsMyError](https://whatismyerror.com/errors/typescript/ts6133-declared-but-never-used)