clean-css-cli
Advanced tools
The clean-css-cli npm package is a command-line interface for the clean-css library, which is used to minify and optimize CSS files. It provides a simple way to reduce the size of CSS files by removing unnecessary whitespace, comments, and other redundant elements, making the CSS more efficient for web use.
Minify CSS
This command minifies the input CSS file (input.css) and writes the optimized output to a new file (output.css).
npx clean-css-cli -o output.css input.cssMinify Multiple CSS Files
This command takes multiple CSS files (file1.css and file2.css) and combines and minifies them into a single output file (output.css).
npx clean-css-cli -o output.css file1.css file2.cssMinify CSS with Source Maps
This command minifies the input CSS file (input.css) and generates a source map along with the optimized output file (output.css). Source maps help in debugging the minified CSS.
npx clean-css-cli --source-map -o output.css input.cssMinify CSS with Advanced Optimizations
This command applies advanced optimizations (level 2) while minifying the input CSS file (input.css) and writes the optimized output to a new file (output.css).
npx clean-css-cli --level 2 -o output.css input.cssThe csso-cli package is a command-line interface for the CSSO (CSS Optimizer) library. It provides similar functionality to clean-css-cli, allowing users to minify and optimize CSS files. CSSO focuses on structural optimizations and can sometimes achieve better compression rates than clean-css-cli.
The uglifycss package is another tool for minifying CSS files. It is simpler and less feature-rich compared to clean-css-cli but can be a good choice for basic CSS minification tasks. It focuses on removing whitespace and comments to reduce file size.
The cssnano package is a modular minifier based on PostCSS. It provides a wide range of optimizations and is highly configurable. Compared to clean-css-cli, cssnano offers more flexibility and can be integrated into build systems like webpack and Gulp.
clean-css-cli is a command-line interface to clean-css - fast and efficient CSS optimizer for Node.js.
Previously a part of clean-css it's a separate package since clean-css 4.0.
Table of Contents
clean-css-cli requires Node.js 10.0+ (tested on Linux)
npm install clean-css-cli -g
Note: Global install via -g option is recommended unless you want to execute the binary via a relative path, i.e. ./node_modules/.bin/cleancss
cleancss -o one.min.css one.css
clean-css-cli 5.5 introduces the following changes / features:
--watch switch, which makes cleancss re-run optimizations when watched file(s) change.clean-css-cli 5.1 introduces the following changes / features:
!path/to/file as a way of telling cleancss to ignore such file, also accepts any available glob patterns.clean-css-cli 5.0 introduces the following changes / features:
--batch option (off by default) which processes input files one by one without joining them together;--batch-suffix option to specify what gets appended to output filename in batch mode;--skip-rebase option has been removed as rebasing URLs is disabled by default now--with-rebase option is added if you really want URLs rebasingclean-css-cli 4.3 introduces the following changes / features:
--input-source-map option which accepts a path to input source map file.clean-css-cli 4.2 introduces the following changes / features:
clean-css-cli 4.1 introduces the following changes / features:
--remove-inlined-files option for removing files inlined in <source-file ...> or via @import statements;--compatibility selectors.mergeLimit=512;beforeMinify callback as a second argument to CLI module, see example use case.clean-css-cli 4.0 introduces some breaking changes:
--root and --relativeTo options are replaced by a single option taken from --output path - this means that rebasing URLs and import inlining is much simpler but may not be (YMMV) as powerful as in 3.x;--rounding-precision is disabled by default;--rounding-precision applies to all units now, not only px as in 3.x;--skip-import and --skip-import-from are merged into --inline option which defaults to local. Remote @import rules are NOT inlined by default anymore;--timeout option to --inline-timeout;//fonts.googleapis.com/css?family=Domine:700, are not inlined anymore;--compatibility ie9 option;--rounding-precision, --s0, and --s1 options to level 1 optimization options, see examples;--skip-media-merging, --skip-restructuring, --semantic-merging, and --skip-shorthand-compacting to level 2 optimizations options, see examples below;--keep-breaks option is replaced with --format keep-breaks to ease transition;--skip-aggressive-merging option is removed as aggressive merging is replaced by smarter override merging.-b, --batch If enabled, optimizes input files one by one instead of joining them together
-c, --compatibility [ie7|ie8] Force compatibility mode (see Readme for advanced examples)
-d, --debug Shows debug information (minification time & compression efficiency)
-f, --format <options> Controls output formatting, see examples below
-h, --help output usage information
-o, --output [output-file] Use [output-file] as output instead of STDOUT
-O <n> [optimizations] Turn on level <n> optimizations; optionally accepts a list of fine-grained options, defaults to `1`, IMPORTANT: the prefix is O (a capital o letter), NOT a 0 (zero, a number)
-v, --version output the version number
--inline [rules] Enables inlining for listed sources (defaults to `local`)
--inline-timeout [seconds] Per connection timeout when fetching remote stylesheets (defaults to 5 seconds)
--input-source-map [file] Specifies the path of the input source map file
--remove-inlined-files Remove files inlined in <source-file ...> or via `@import` statements
--source-map Enables building input's source map
--source-map-inline-sources Enables inlining sources inside source maps
--with-rebase Enables URLs rebasing
There is a certain number of compatibility mode shortcuts, namely:
--compatibility '*' (default) - Internet Explorer 10+ compatibility mode--compatibility ie9 - Internet Explorer 9+ compatibility mode--compatibility ie8 - Internet Explorer 8+ compatibility mode--compatibility ie7 - Internet Explorer 7+ compatibility modeEach of these modes is an alias to a fine grained configuration, with the following options available:
cleancss --compatibility '*,-properties.urlQuotes'
cleancss --compatibility '*,+properties.ieBangHack,+properties.ieFilters'
# [+-]colors.opacity controls `rgba()` / `hsla()` color support; defaults to `on` (+)
# [+-]properties.backgroundClipMerging controls background-clip merging into shorthand; defaults to `on` (+)
# [+-]properties.backgroundOriginMerging controls background-origin merging into shorthand; defaults to `on` (+)
# [+-]properties.backgroundSizeMerging controls background-size merging into shorthand; defaults to `on` (+)
# [+-]properties.colors controls color optimizations; defaults to `on` (+)
# [+-]properties.ieBangHack controls keeping IE bang hack; defaults to `off` (-)
# [+-]properties.ieFilters controls keeping IE `filter` / `-ms-filter`; defaults to `off` (-)
# [+-]properties.iePrefixHack controls keeping IE prefix hack; defaults to `off` (-)
# [+-]properties.ieSuffixHack controls keeping IE suffix hack; defaults to `off` (-)
# [+-]properties.merging controls property merging based on understandability; defaults to `on` (+)
# [+-]properties.shorterLengthUnits controls shortening pixel units into `pc`, `pt`, or `in` units; defaults to `off` (-)
# [+-]properties.spaceAfterClosingBrace controls keeping space after closing brace - `url() no-repeat` cleancss --compatibility '*,into `url('roperties.no-repeat`; defaults to `on` (+)
# [+-]properties.urlQuotes controls keeping quoting inside `url()`; defaults to `off` (-)
# [+-]properties.zeroUnitsf units `0` value; defaults to `on` (+)
# [+-]selectors.adjacentSpace controls extra space before `nav` element; defaults to `off` (-)
# [+-]selectors.ie7Hack controls removal of IE7 selector hacks, e.g. `*+html...`; defaults to `on` (+)
# [+-]units.ch controls treating `ch` as a supported unit; defaults to `on` (+)
# [+-]units.in controls treating `in` as a supported unit; defaults to `on` (+)
# [+-]units.pc controls treating `pc` as a supported unit; defaults to `on` (+)
# [+-]units.pt controls treating `pt` as a supported unit; defaults to `on` (+)
# [+-]units.rem controls treating `rem` as a supported unit; defaults to `on` (+)
# [+-]units.vh controls treating `vh` as a supported unit; defaults to `on` (+)
# [+-]units.vm controls treating `vm` as a supported unit; defaults to `on` (+)
# [+-]units.vmax controls treating `vmax` as a supported unit; defaults to `on` (+)
# [+-]units.vmin controls treating `vmin` as a supported unit; defaults to `on` (+)
You can also chain more rules after a shortcut when setting a compatibility:
cleancss --compatibility 'ie9,-colors.opacity,-units.rem' one.css
The --format option accept the following options:
cleancss --format beautify one.css
cleancss --format keep-breaks one.css
cleancss --format 'indentBy:1;indentWith:tab' one.css
cleancss --format 'breaks:afterBlockBegins=on;spaces:aroundSelectorRelation=on' one.css
# `breaks` controls where to insert breaks
# `afterAtRule` controls if a line break comes after an at-rule; e.g. `@charset`; defaults to `off` (alias to `false`)
# `afterBlockBegins` controls if a line break comes after a block begins; e.g. `@media`; defaults to `off`
# `afterBlockEnds` controls if a line break comes after a block ends, defaults to `off`
# `afterComment` controls if a line break comes after a comment; defaults to `off`
# `afterProperty` controls if a line break comes after a property; defaults to `off`
# `afterRuleBegins` controls if a line break comes after a rule begins; defaults to `off`
# `afterRuleEnds` controls if a line break comes after a rule ends; defaults to `off`
# `beforeBlockEnds` controls if a line break comes before a block ends; defaults to `off`
# `betweenSelectors` controls if a line break comes between selectors; defaults to `off`
# `breakWith` controls the new line character, can be `windows` or `unix` (aliased via `crlf` and `lf`); defaults to system one, so former on Windows and latter on Unix
# `indentBy` controls number of characters to indent with; defaults to `0`
# `indentWith` controls a character to indent with, can be `space` or `tab`; defaults to `space`
# `spaces` controls where to insert spaces
# `aroundSelectorRelation` controls if spaces come around selector relations; e.g. `div > a`; defaults to `off`
# `beforeBlockBegins` controls if a space comes before a block begins; e.g. `.block {`; defaults to `off`
# `beforeValue` controls if a space comes before a value; e.g. `width: 1rem`; defaults to `off`
# `wrapAt` controls maximum line length; defaults to `off`
--inline option whitelists which @import rules will be processed, e.g.
cleancss --inline local one.css # default
cleancss --inline all # same as local,remote
cleancss --inline local,mydomain.example.com one.css
cleancss --inline 'local,remote,!fonts.googleapis.com' one.css
The -O option can be either 0, 1 (default), or 2, e.g.
cleancss -O2 one.css
or a fine-grained configuration given via a string.
Please note that level 1 optimization options are generally safe while level 2 optimizations should be safe for most users.
Important: The -O option is using the capital letter O (as in "Oscar"), not the number zero.
Level 0 optimizations simply means "no optimizations". Use it when you'd like to inline imports and / or rebase URLs but skip everything else, e.g.
cleancss -O0 one.css
Level 1 optimizations (default) operate on single properties only, e.g. can remove units when not required, turn rgb colors to a shorter hex representation, remove comments, etc
Here is a full list of available options:
cleancss -O1 one.css
cleancss -O1 removeQuotes:off;roundingPrecision:4;specialComments:1 one.css
# `cleanupCharsets` controls `@charset` moving to the front of a stylesheet; defaults to `on`
# `normalizeUrls` controls URL normalzation; default to `on`
# `optimizeBackground` controls `background` property optimizatons; defaults to `on`
# `optimizeBorderRadius` controls `border-radius` property optimizatons; defaults to `on`
# `optimizeFilter` controls `filter` property optimizatons; defaults to `on`
# `optimizeFontWeight` controls `font-weight` property optimizatons; defaults to `on`
# `optimizeOutline` controls `outline` property optimizatons; defaults to `on`
# `removeEmpty` controls removing empty rules and nested blocks; defaults to `on` (since 4.1.0)
# `removeNegativePaddings` controls removing negative paddings; defaults to `on`
# `removeQuotes` controls removing quotes when unnecessary; defaults to `on`
# `removeWhitespace` controls removing unused whitespace; defaults to `on`
# `replaceMultipleZeros` contols removing redundant zeros; defaults to `on`
# `replaceTimeUnits` controls replacing time units with shorter values; defaults to `on
# `replaceZeroUnits` controls replacing zero values with units; defaults to `on`
# `roundingPrecision` rounds pixel values to `N` decimal places; `off` disables rounding; defaults to `off`
# `selectorsSortingMethod` denotes selector sorting method; can be `natural` or `standard`; defaults to `standard`
# `specialComments` denotes a number of /*! ... */ comments preserved; defaults to `all`
# `tidyAtRules` controls at-rules (e.g. `@charset`, `@import`) optimizing; defaults to `on`
# `tidyBlockScopes` controls block scopes (e.g. `@media`) optimizing; defaults to `on`
# `tidySelectors` controls selectors optimizing; defaults to `on`
There is an all shortcut for toggling all options at the same time, e.g.
cleancss -O1 'all:off;tidySelectors:on' one.css
Level 2 optimizations operate at rules or multiple properties level, e.g. can remove duplicate rules, remove properties redefined further down a stylesheet, or restructure rules by moving them around.
Please note that if level 2 optimizations are turned on then, unless explicitely disabled, level 1 optimizations are applied as well.
Here is a full list of available options:
cleancss -O2 one.css
cleancss -O2 mergeMedia:off;restructureRules:off;mergeSemantically:on;mergeIntoShorthands:off one.css
# `mergeAdjacentRules` controls adjacent rules merging; defaults to `on`
# `mergeIntoShorthands` controls merging properties into shorthands; defaults to `on`
# `mergeMedia` controls `@media` merging; defaults to `on`
# `mergeNonAdjacentRules` controls non-adjacent rule merging; defaults to `on`
# `mergeSemantically` controls semantic merging; defaults to `off`
# `overrideProperties` controls property overriding based on understandability; defaults to `on`
# `reduceNonAdjacentRules` controls non-adjacent rule reducing; defaults to `on`
# `removeDuplicateFontRules` controls duplicate `@font-face` removing; defaults to `on`
# `removeDuplicateMediaBlocks` controls duplicate `@media` removing; defaults to `on`
# `removeDuplicateRules` controls duplicate rules removing; defaults to `on`
# `removeEmpty` controls removing empty rules and nested blocks; defaults to `on` (since 4.1.0)
# `removeUnusedAtRules` controls unused at rule removing; defaults to `off` (since 4.1.0)
# `restructureRules` controls rule restructuring; defaults to `off`
# `skipProperties` controls which properties won\'t be optimized, defaults to empty list which means all will be optimized (since 4.1.0)
There is an all shortcut for toggling all options at the same time, e.g.
cleancss -O2 'all:off;removeDuplicateRules:on' one.css
clean-css-cli can also be used as a module in a way of enhancing its functionality in a programmatic way, e.g.
#!/usr/bin/env node
var cleanCssCli = require('clean-css-cli');
var customPlugin = {
level1: {
value: function (propertyName, propertyValue, options) {
if (propertyName == 'background-image' && propertyValue.indexOf('../valid/path/to') == -1) {
return propertyValue.replace('url(', 'url(../valid/path/to/');
} else {
return propertyValue;
}
}
}
}
return cleanCssCli(process, function (cleanCss) {
cleanCss.options.plugins.level1Value.push(customPlugin.level1.value);
});
More answers can be found in clean-css FAQ section.
It can be done by passing in paths to multiple files, e.g.
cleancss -o merged.min.css one.css two.css three.css
Since version 4.1.0 it can also be done using glob pattern matching, e.g.
cleancss -o merged.min.css *.css
Since clean-css-cli 5.0 you can optimize files one by one, without joining them into one output file, e.g.
cleancss --batch styles/*.css
By default it will pick up every single file from styles directory, optimize it, add a -min suffix to filename (before extension), and write it to disk.
You can use --batch-suffix option to customize the -min suffix, e.g.
cleancss --batch --batch-suffix '.min' styles/*.css # output will have `.min` suffix before `.css`, e.g. styles.min.css
or
cleancss --batch --batch-suffix '' styles/*.css # output files will OVERRIDE input files
Remember you can use glob matching to match exactly the files you want.
Since clean-css-cli 5.1 you can also use a negated pattern to exclude some files from being matched, e.g.
cleancss --batch styles/*.css !styles/*.min.css
The level 1 roundingPrecision optimization option accept a string with per-unit rounding precision settings, e.g.
cleancss -O1 roundingPrecision:all=3,px=5
which sets all units rounding precision to 3 digits except px unit precision of 5 digits.
clean-css-cli will rebase paths it automatically for you when full paths to input files are passed, and --with-rebase & --output options are used, e.g
/*! one.css */
a {
background:url(image.png)
}
cleancss --with-rebase -o build/one.min.css one.css
/*! build/one.min.css */
a{background:url(../image.png)}
Using -O option twice and specifying optimization options in each, e.g.
cleancss -O1 all:on,normalizeUrls:off -O2 restructureRules:on one.css
will apply level 1 optimizations, except url normalization, and default level 2 optimizations with rule restructuring.
See CONTRIBUTING.md.
First clone the sources:
git clone git@github.com:clean-css/clean-css-cli.git
then install dependencies:
cd clean-css-cli
npm install
then use any of the following commands to verify your copy:
npm run check # to lint JS sources with [JSHint](https://github.com/jshint/jshint/)
npm test # to run all tests
clean-css-cli is released under the MIT License.
FAQs
A command-line interface to clean-css CSS optimization library
The npm package clean-css-cli receives a total of 79,050 weekly downloads. As such, clean-css-cli popularity was classified as popular.
We found that clean-css-cli demonstrated a healthy version release cadence and project activity because the last version was released less than a year ago. It has 1 open source maintainer collaborating on the project.
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