• Prevented percent sign removal in flex/-ms-flex (#410)
• Fixed restructuring optimisation in some cases (@charlessuh & @chsuh, #358, #411)
• Bumped dependencies (@AviVahl, #409)

4.0.2 (October 28, 2019)

• Fixed clean stage to avoid exceptions when source has unparsed or bad parts (#380)
• Fixed wrong percentage sign removal for zero values (#395)

4.0.1 (October 22, 2019)

• Bumped CSSTree to 1.0.0-alpha.37 to avoid source map generation inconsistency across Node.js versions

4.0.0 (October 21, 2019)

• Dropped support for Node.js < 8
• Refreshed dev dependencies and scripts
• Bumped CSSTree to 1.0.0-alpha.36 (#399)
• Changed bundle files: dist/csso.js and dist/csso.min.js instead single dist/csso-browser.js (min version)
• Expose compress() as syntax.compress()

3.5.1 (June 7, 2018)

• Bumped CSSTree to 1.0.0-alpha.29 (fixes some issues)

3.5.0 (January 14, 2018)

• Migrated to CSSTree 1.0.0-alpha.27

3.4.0 (November 3, 2017)

• Added percent sign removal for zero percentages for some properties that is safe (@RubaXa, #286)
• Removed unit removal for zero values in -ms-flex due it breaks flex in IE10/11 (#362)
• Improved performance of selectors comparison (@smelukov, #343)

3.3.1 (October 17, 2017)

• Fixed merge of position declarations when sticky fallback is using (@gruzzilkin, #356)

3.3.0 (October 12, 2017)

• Migrated to CSSTree 1.0.0-alpha25
  • Changed AST format (see CSSTree change log for details)
  • Fixed performance issue when generate CSS with source map (quadratic increase in time depending on the size of the CSS)

3.2.0 (September 10, 2017)

• Fixed named color compression to apply only when an identifier is guaranteed to be a color
• Added lifting of @keyframes to the beginning of style sheet (chunk), but after @charset and @import rules
• Added removal of @keyframes, @media and @supports with no prelude
• Added removal of duplicate @keyframes (#202)
• Added new option forceMediaMerge to force media rules merging. It's unsafe in general, but works fine in many cases. Use it on your own risk (#350)
• Bumped CSSTree to 1.0.0-alpha23

3.1.1 (April 25, 2017)

• Fixed crash on a number processing when it used not in a list (#335)

3.1.0 (April 24, 2017)

• Implemented optimisation for none keyword in border and outline properties (@zoobestik, #41)
• Implemented replacing rgba(x, x, x, 0) to transparent
• Fixed plus sign omitting for numbers following identifier, hex color, number or unicode range, since it can change the meaning of CSS (e.g. calc(1px+2px) has been optimized to calc(1px2px) before, now it stays the same)
• Improved usage filtering for nested selectors (i.e. for :nth-*(), :has(), :matches and other pseudos)
• Implemented blacklist filtering in usage (#334, see Black list filtering)
• Improved white space removing, now white spaces are removing in the beginning and at the ending of sequences, and between stylesheet and block nodes
• Bumped CSSTree to 1.0.0-alpha19

3.0.1 (March 14, 2017)

• Fixed declaration merging when declaration contains an !important

3.0.0 (March 13, 2017)

• Migrated to CSSTree as AST backend and exposed its API behind syntax property
• Extracted CLI into standalone package css/csso-cli

2.3.1 (January 6, 2017)

• Added \0 IE hack support (#320)

2.3.0 (October 25, 2016)

• Added beforeCompress and afterCompress options support (#316)
• Fixed crash on empty argument in function (#317)

2.2.1 (July 25, 2016)

• Fixed shorthand optimisation issue when value has a color value or something unknown (#311)
• Fixed cursor broken fallback (#306)

2.2.0 (June 23, 2016)

• Implement AST cloning by adding clone() function and clone option for compress() function (#296)
• Fix parse and translate attribute selector with flags but w/o operator (i.e. [attrName i])
• Don't merge rules with flagged attribute selectors with others (#291)
• Take in account functions when merge TRBL-properties (#297, thanks to @ArturAralin)
• Improve partial merge (#304)
• Tweak scanner, reduce code deoptimizations and other small improvements

2.1.1 (May 11, 2016)

• Fix wrong declaration with \9 hack merge (#295)

2.1.0 (May 8, 2016)

• New option comments to specify what comments to left: exclamation, first-exclamation and none
• Add offset to CSS parse error details
• Fix token offset computation

2.0.0 (April 5, 2016)

• No more gonzales AST format and related code
• minify() and minifyBlock() is always return an object as result now (i.e. { css: String, map: SourceMapGenerator or null })
• parse()
  • Returns AST in new format (so called internal)
  • Dynamic scanner implemented
  • New AST format + dynamic scanner = performance boost and less memory consumption
  • No more context argument, context should be specified via options
  • Supported contexts now: stylesheet, atrule, atruleExpression, ruleset, selector, simpleSelector, block, declaration and value
  • Drop needPositions option, positions option should be used instead
  • Drop needInfo option, info object is attaching to nodes when some information is requested by options
  • options should be an object, otherwise it treats as empty object
• compress()
  • No more AST converting (performance boost and less memory consumption)
  • Drop outputAst option
  • Returns an object as result instead of AST (i.e. { ast: Object })
• Drop methods: justDoIt(), stringify(), cleanInfo()

1.8.1 (March 30, 2016)

• Don't remove spaces after function/braces/urls since unsafe (#289)

1.8.0 (March 24, 2016)

• Usage data support:
  • Filter rulesets by tag names, class names and ids white lists.
  • More aggressive ruleset moving using class name scopes information.
  • New CLI option --usage to pass usage data file.
• Improve initial ruleset merge
  • Change order of ruleset processing, now it's left to right. Previously unmerged rulesets may prevent lookup and other rulesets merge.
  • Difference in pseudo signature just prevents ruleset merging, but don't stop lookup.
  • Simplify block comparison (performance).
• New method csso.minifyBlock() for css block compression (e.g. style attribute content).
• Ruleset merge improvement: at-rules with block (like @media or @supports) now can be skipped during ruleset merge lookup if doesn't contain something prevents it.
• FIX: Add negation (:not()) to pseudo signature to avoid unsafe merge (old browsers doesn't support it).
• FIX: Check nested parts of value when compute compatibility. It fixes unsafe property merging.

1.7.1 (March 16, 2016)

• pass block mode to tokenizer for correct parsing of declarations properties with // hack
• fix wrongly @import and @charset removal on double exclamation comment

1.7.0 (March 10, 2016)

• support for CSS Custom Properties (#279)
• rework RTBL properties merge – better merge for values with special units and don't merge values with CSS-wide keywords (#255)
• remove redundant universal selectors (#178)
• take in account !important when check for property overriding (#280)
• don't merge text-align declarations with some values (#281)
• add spaces around /deep/ combinator on translate, since it together with universal selector can produce a comment
• better keyword and property name resolving (tolerant to hacks and so on)
• integration improvements
  • compression log function could be customized by logger option for compress() and minify()
  • make possible to set initial line and column for parser

1.6.4 (March 1, 2016)

• npm publish issue (#276)

1.6.3 (February 29, 2016)

• add file to generated source map since other tools can relay on it in source map transform chain

1.6.2 (February 29, 2016)

• tweak some parse error messages and their positions
• fix :not() parsing and selector groups in :not() is supported now (#215)
• needPosition parser option is deprecated, positions option should be used instead (needPosition is used still if positions option omitted)
• expose internal AST API as csso.internal.*
• minify() adds sourcesContent by default when source map is generated
• bring back support for node.js 0.10 until major release (#275)

1.6.1 (February 28, 2016)

• fix exception on zero length dimension compress outside declaration (#273)

1.6.0 (February 27, 2016)

• source maps support
• parser remake:
  • various parsing issues fixed
  • fix unicode sequence processing in ident (#191)
  • support for flags in attribute selector (#270)
  • position (line and column) of parse error (#109)
  • 4x performance boost, less memory consumption
• compressor refactoring
  • internal AST is using doubly linked lists (with safe transformation support during iteration) instead of arrays
  • rename restructuring to restructure option for minify()/compress() (restructuring is alias for restructure now, with lower priority)
  • unquote urls when possible (#141, #60)
• setup code coverage and a number of related fixes
• add eslint to check unused things

1.5.4 (January 27, 2016)

• one more fix (in restructRuleset this time) with merge of rulesets when a ruleset with same specificity places between them (#264)
• disable partial merge of rulesets in @keyframes rulesets (until sure it's correct)

1.5.3 (January 25, 2016)

• don't override display values with different browser support (#259)
• fix publish issue (one of modules leak in development state)

1.5.2 (January 24, 2016)

• don't merge rulesets if between them a ruleset with same specificity (#264)

1.5.1 (January 14, 2016)

• ensure - is not used as an identifier in attribute selectors (thanks to @mathiasbynens)
• fix broken justDoIt() function
• various small fixes

1.5.0 (January 14, 2016)

Parser

• attach minus to number

Compressor

• split code base into small modules and related refactoring
• introduce internal AST format for compressor (gonzales→internal and internal→gonzales convertors, walkers, translator)
• various optimizations: no snapshots, using caches and indexes
• sort selectors, merge selectors in alphabet order
• compute selector's specificity
• better ruleset restructuring, improve compression of partially equal blocks
• better ruleset merge – not only closest but also disjoined by other rulesets when safe
• join @media with same query
• outputAst – new option to specify output AST format (gonzales by default for backward compatibility)
• remove quotes surrounding attribute values in attribute selectors when possible (#73)
• replace from→0% and 100%→to at @keyframes (#205)
• prevent partial merge of rulesets at @keyframes (#80, #197)

API

• walker for gonzales AST was implemented

CLI

• new option --stat (output stat in stderr)
• new optional parameter level for --debug option

1.4.4 (December 10, 2015)

• prevent removal of spaces after braces that before identifier that breaking at-rules expressions (#258)

1.4.3 (December 4, 2015)

• fix unicode-range parsing that cause to wrong function detection (#250)

1.4.2 (November 9, 2015)

• allow spaces between progid: and rest part of value for IE's filter property as autoprefixer generates this kind of code (#249)
• fixes for Windows:
  • correct processing new lines
  • normalize file content in test suite
• fixes to work in strict mode (#252)
• init compressor dictionaries for every css block (#248, #251)
• bump uglify-js version

1.4.1 (October 20, 2015)

• allow merge for display property (#167, #244)
• more accurate rect (clip property value) merge
• fix typo when specifying options in cli (thanks to @Taritsyn)
• fix safe unit values merge with keyword values (#244)
• fix wrong descendant combinator removal (#246)
• build browser version on prepublish (thanks to @silentroach)
• parser: store whitespaces as single token (performance and reduce memory consumption)
• rearrange compress tests layout

1.4 (October 16, 2015)

Bringing project back to life. Changed files structure, cleaned up and refactored most of sources.

Common

• single code base (no more src folder)
• build browser version with browserify (no more make, and web folder), browser version is available at dist/csso-browser.js
• main file is lib/index.js now
• minimal node.js version is 0.12 now
• restrict file list to publish on npm (no more useless folders and files in package)
• add jscs to control code style
• automate gh-pages update
• util functions reworked
• translator reworked
• test suite reworked
• compressor refactored
• initial parser refactoring

API

• new method minify(src, options), options:
  • restructuring – if set to false, disable structure optimisations (true by default)
  • debug - outputs intermediate state of CSS during compression (false by default)
• deprecate justDoIt() method (use minify instead)
• rename treeToString() method to stringify()
• drop printTree() method
• AST node info
  • column and offset added
  • ln renamed to line
  • fix line counting across multiple files and input with CR LF (#147)

CLI

• completely reworked, use clap to parse argv
• add support for input from stdin (#128)
• drop undocumented and obsoleted options --rule and --parser (suppose nobody use it)
• drop -off alias for --restructure-off as incorrect (only one letter options should starts with single -)
• new option --debug that reflecting to options.debug for minify

Parsing and optimizations

• keep all exclamation comments (#194)
• add /deep/ combinator support (#209)
• attribute selector
  • allow colon in attribute name (#237)
  • support for namespaces (#233)
• color
  • support all css/html colors
  • convert hsla to rgba and hls to rgb
  • convert rgba with 1 as alpha value to rgb (#122)
  • interpolate rgb and rgba percentage values to absolute values
  • replace percentage values in rgba for normalized/interpolated values
  • lowercase hex colors and color names (#169)
  • fix color minification when hex value replaced for color name (#176)
  • fit rgb values to 0..255 range (#181)
• calc
  • remove spaces for multiple operator in calc
  • don't remove units inside calc (#222)
  • fix wrong white space removal around + and - (#228)
• don't remove units in flex property as it could change value meaning (#200)
• don't merge \9 hack values (#231)
• merge property values only if they have the same functions (#150, #227)
• don't merge property values with some sort of units (#140, #161)
• fix !important issue for top-right-bottom-left properties (#189)
• fix top-right-bottom-left properties merge (#139, #175)
• support for unicode-range (#148)
• don't crash on ruleset with no selector (#135)
• tolerant to class names that starts with digit (#99, #105)
• fix background compressing (#170)

1.3.12 (October 8, 2015)

• Case insensitive check for !important (#187)
• Fix problems with using csso as cli command on Windows (#83, #136, #142 and others)
• Remove byte order marker (the UTF-8 BOM) from input
• Don't strip space between funktion-funktion and funktion-vhash (#134)
• Don't merge TRBL values having \9 (hack for IE8 in bootstrap) (#159, #214, #230, #231 and others)
• Don't strip units off dimensions of non-length (#226, #229 and others)

1.3.7 (February 11, 2013)

• Gonzales 1.0.7.

1.3.6 (November 26, 2012)

• Gonzales 1.0.6.

1.3.5 (October 28, 2012)

• Gonzales 1.0.5.
• Protecting copyright notices in CSS: https://github.com/css/csso/issues/92
• Zero CSS throws an error: https://github.com/css/csso/issues/96
• Don't minify the second 0s in Firefox for animations: https://github.com/css/csso/issues/100
• Japan manual
• BEM ready documentation

1.3.4 (October 10, 2012)