babel-plugin-remove-unused-vars

2.2.0 verified Sat Apr 25 auth: no javascript

A Babel plugin that automatically removes unused variables, imports, function arguments, and destructured bindings from JavaScript code, acting as a Babel-based autofix for ESLint's no-unused-vars rule. As of version 2.2.0, it supports source-to-source transformations and is intended for use as a build tool to clean up code. The plugin runs via Babel CLI or programmatically and handles common cases but has known limitations with deep assignment expressions. It is released under the MIT license with moderate maintenance cadence on GitHub, positioned as a more aggressive alternative to manual lint fixes or tree-shaking.

Common errors

error Error: Cannot find module 'babel-plugin-remove-unused-vars' ↓

cause Plugin not installed or not in node_modules.

fix

Run 'npm install --save-dev babel-plugin-remove-unused-vars' and ensure working directory has node_modules.

error TypeError: babel.transformSync is not a function ↓

cause Using a string plugin name instead of the plugin function reference when calling Babel programmatically.

fix

Use: babel.transformSync(code, { plugins: [require('babel-plugin-remove-unused-vars')] })

error Unexpected token (1:0) when running Babel with --no-babelrc ↓

cause Missing @babel/preset-env or other presets; --no-babelrc disables .babelrc but the plugin alone doesn't parse modern syntax.

fix

Add presets explicitly: npx babel --no-babelrc --presets @babel/preset-env --plugins babel-plugin-remove-unused-vars

Warnings

gotcha Plugin may produce false positives (removing actually used variables) or false negatives (keeping unused variables). Always review git diff after transformation. ↓

fix Run locally, inspect output with 'git diff', revert false removals manually.

gotcha Deep assignment expressions (e.g., const a = foo(b = something())) are not fully handled. The right side may be removed even if the left side is used. ↓

fix Avoid deep assignments, or manually adjust after transformation.

gotcha Plugin is intended for source-to-source transformation, not for minification or bundling. It should be run early in the build pipeline. ↓

fix Run before other transformations like minification.

Install

npm install babel-plugin-remove-unused-vars

yarn add babel-plugin-remove-unused-vars

pnpm add babel-plugin-remove-unused-vars

Imports

default

wrong

import plugin from 'babel-plugin-remove-unused-vars'

correct

module.exports = require('babel-plugin-remove-unused-vars')

Plugin is CommonJS only; use require() in .babelrc or babel.config.js

PluginObj

wrong

import { PluginObj } from 'babel-plugin-remove-unused-vars'

correct

const plugin = require('babel-plugin-remove-unused-vars')

No named exports; use default require

programmatic usage

wrong

babel.transformSync(code, { plugins: ['babel-plugin-remove-unused-vars'] })

correct

const babel = require('@babel/core'); const plugin = require('babel-plugin-remove-unused-vars'); babel.transformSync(code, { plugins: [plugin] })

When using programmatically, pass the plugin function reference, not a string

Quickstart

Shows installation, configuration, CLI usage, and a simple transformation that removes unused imports and variables.

// Install: npm install --save-dev babel-plugin-remove-unused-vars
// .babelrc
{
  "plugins": ["babel-plugin-remove-unused-vars"]
}

// Or via CLI:
// npx babel --no-babelrc --retain-lines --plugins babel-plugin-remove-unused-vars --out-dir dist/ src/

// Input: src/index.js
import { unused } from './utils';
const a = 1;
const b = a;
console.log(b);

// Output: dist/index.js
import {} from './utils';
const b = 1;
console.log(b);