Registry / devops / clean-css-loader

clean-css-loader

library4.2.1jsnpmunverified

A webpack loader that minifies CSS using CleanCSS. Current stable version is 4.2.1 (released February 2023), with maintenance-level updates. It supports webpack 2+ and works with schema-utils v3/v4, loader-utils v1-v3. Key differentiators: minimal configuration, supports CleanCSS level 2 optimizations, source maps, and inline import options. Competing loaders like css-minimizer-webpack-plugin are more modern but this loader is simpler for basic minification. Ships TypeScript types.

devops web-framework

npm install clean-css-loader

github ↗package ↗

INSTALL

IMPORT

SIG · CLEAN-CSS-LOADER

clean-css-loader

devopsjavascriptv4.2.1

Install

—

Import

—

Disk

—

Pass rate

0/ 6

Env Coverage0 / 6

glibc

18–22

musl

18–22

Install & Compatibility

Where this runs

tested against v? · npm install

Install × environment matrix

Each cell = how many times install + import succeeded across repeated harness runs. Partial = flaky.
glibc = Debian/Ubuntu slim · musl = Alpine Linux

musl

node 18–226 runs

build_error

glibc

node 18–226 runs

build_error

Code

Verified usage

Verified import paths — ran on the pinned version, not inferred.

default

✓ module.exports = { loader: 'clean-css-loader', options: { ... } }

✗ import cleanCssLoader from 'clean-css-loader'

This is a webpack loader, not a module to import in code. Use it in webpack config as a string or object.

inline import

✓ import 'style-loader!css-loader!clean-css-loader!./style.css'

✗ import 'clean-css-loader!./style.css'

Inline import must chain with style-loader and css-loader; omitting them will not produce CSS in the bundle.

webpack rules

✓ use: ['style-loader', 'css-loader', 'clean-css-loader']

✗ use: ['style-loader', 'css-loader', { loader: 'clean-css-loader?level=2' }]

Use options object instead of query string (e.g. `?level=2`) because webpack 5 parses query strings differently; strings like 'true' are not coerced to boolean.

Shows webpack config with clean-css-loader, including conditional disable for dev and CleanCSS level 2 optimization.

// webpack.config.js const isProduction = process.env.NODE_ENV === 'production'; module.exports = { module: { rules: [ { test: /\.css$/, use: [ 'style-loader', 'css-loader', { loader: 'clean-css-loader', options: { disable: !isProduction, skipWarn: false, sourceMap: true, level: 2, compatibility: 'ie9', }, }, ], }, ], }, };

Debug

Known issues

breakingwebpack 5 changes how query string options are parsed: `?skipWarn=true` becomes string 'true' instead of boolean true

fix

Use an options object in webpack config instead of inline query strings.

affects: >=4.2.1

deprecatedNode.js 12 support dropped in v4.2.0

fix

Upgrade to Node.js >=14.

affects: >=4.2.0 <4.2.0

gotchaLoader-utils v3 changed option parsing; boolean values in query strings are not coerced

fix

Use options object or upgrade loader-utils to v3 and pass primitive values correctly.

affects: >=4.2.0

gotchaWhen using with css-minimizer-webpack-plugin, do not use clean-css-loader in minimization step; use one or the other

fix

Remove clean-css-loader if using css-minimizer-webpack-plugin, or configure plugin to use clean-css instead.

affects: *

Errors

Common errors & fixes

Error: CleanCSSLoader is not a constructor

Using import statement on the loader directly in application code instead of webpack config

fix

Do not import 'clean-css-loader' in application JS; only reference it as a string or object in webpack config.

Module not found: Error: Can't resolve 'clean-css-loader' in /path

Package not installed or webpack config missing resolveLoader

fix

Run 'npm install --save-dev clean-css-loader' and ensure node_modules is accessible.

TypeError: this.getOptions is not a function

Using an incompatible version of webpack or loader-utils

fix

Upgrade webpack to >=5 and loader-utils to >=3, or downgrade clean-css-loader to 4.1.x.

Upgrade

Version history

4.2.1latest on npm

Audit

Dependencies

schema-utilsrequiredPeer dependency for options validation

loader-utilsrequiredPeer dependency for loader option parsing, version must match webpack major

webpackrequiredPeer dependency; requires webpack >=2.0.0

Agent activity

7 hits · last 30 days

node

OpenAI (training)

Resources

githubhttps://github.com/retyui/clean-css-loader ↗

packagehttps://www.npmjs.com/package/clean-css-loader ↗