CSS minifier with structural optimisations. 

CSS minifier with structural optimisations

tadatuta

lahmatiy

afelix

csso

- Trim Custom Property values when possible (#393)

- Fixed removing unit for zero-length dimentions in `min()`, `max()` and `clamp()` functions (#426)

- Fixed crash on bad value in TRBL declaration value (#412)

- Fixed build setup to exclude full `mdn/data` that reduced the lib size:

    * dist/csso.min.js: 394.4Kb -> 194.2Kb

    * package unpacked size: 1.3 MB -> 586.8 kB

- Bumped [CSSTree](https://github.com/csstree/csstree) to `^1.0.0`

- Fixed wrongly merging of TRBL values when one of them contains `var()` (#420)

- Fixed wrongly merging of pseudo class and element with the same name, e.g. `:-ms-input-placeholder` and `::-ms-input-placeholder` (#383, #416)

- Fixed wrongly merging of `overflow` fallback (#415)

- Prevented percent sign removal in `flex`/`-ms-flex` (#410)

- Fixed restructuring optimisation in some cases (@charlessuh & @chsuh, #358, #411)

- Fixed clean stage to avoid exceptions when source has unparsed or bad parts (#380)

- Fixed wrong percentage sign removal for zero values (#395)

- Bumped CSSTree to [`1.0.0-alpha.37`](https://github.com/csstree/csstree/releases/tag/v1.0.0-alpha.37) to avoid source map generation inconsistency across Node.js versions

- Bumped [CSSTree](https://github.com/csstree/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()`

- Bumped [CSSTree](https://github.com/csstree/csstree) to `1.0.0-alpha.29` (fixes some issues)

- Migrated to [CSSTree](https://github.com/csstree/csstree) `1.0.0-alpha.27`

- 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)

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

- Migrated to [CSSTree](https://github.com/csstree/csstree) `1.0.0-alpha25`

    - Changed AST format (see [CSSTree change log](https://github.com/csstree/csstree/blob/master/HISTORY.md) for details)

    - Fixed performance issue when generate CSS with source map (quadratic increase in time depending on the size of the CSS)

- 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)

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

- 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](https://github.com/css/csso#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

- Fixed declaration merging when declaration contains an `!important`

- Migrated to [CSSTree](https://github.com/csstree/csstree) as AST backend and exposed its API behind `syntax` property

- Extracted CLI into standalone package [css/csso-cli](https://github.com/css/csso-cli)

- Added `beforeCompress` and `afterCompress` options support (#316)

var property = require('css-tree').property;

module.exports = function cleanDeclartion(node, item, list) {

    if (node.value.children && node.value.children.isEmpty()) {

    if (property(node.property).custom) {

        if (/\S/.test(node.value.value)) {

            node.value.value = node.value.value.trim();

var packNumber = require('./Number').pack;

module.exports = function compressDimension(node, item) {

    var value = packNumber(node.value, item);

    if (value === '0' && this.declaration !== null && this.atrulePrelude === null) {

        var unit = node.unit.toLowerCase();

        // only length values can be compressed

        if (!LENGTH_UNIT.hasOwnProperty(unit)) {

        // issue #362: shouldn't remove unit in -ms-flex since it breaks flex in IE10/11

        // issue #200: shouldn't remove unit in flex since it breaks flex in IE10/11

        if (this.declaration.property === '-ms-flex' ||

            this.declaration.property === 'flex') {

        // issue #222: don't remove units inside calc

        if (this.function && this.function.name === 'calc') {

        if (this.function && MATH_FUNCTIONS.hasOwnProperty(this.function.name)) {

var generate = require('css-tree').generate;

var SIDES = ['top', 'right', 'bottom', 'left'];

    'border-right-color': 'border-color',

    'border-bottom-color': 'border-color',

    'border-right-width': 'border-width',

    'border-bottom-width': 'border-width',

    'border-right-style': 'border-style',

    'border-bottom-style': 'border-style',

TRBL.prototype.getValueSequence = function(declaration, count) {

    var hasBadValues = declaration.value.children.some(function(child) {

    var hasBadValues = declaration.value.type !== 'Value' || declaration.value.children.some(function(child) {

                        iehack = child.name;

                        special = child.name;

                    // is not supported until IE11

                    // v* units is too buggy across browsers and better

                    // don't merge values with those units

                    case 'vm': // IE9 supporting "vm" instead of "vmin".

                        special = child.unit;

                if (child.name === 'var') {

                return false; // ignore space

                return true;  // bad value

            important: declaration.important

    if (hasBadValues || values.length > count) {

    if (typeof this.iehack === 'string' && this.iehack !== iehack) {

    this.iehack = iehack; // move outside

TRBL.prototype.canOverride = function(side, value) {

    return !currentValue || (value.important && !currentValue.important);

TRBL.prototype.add = function(name, declaration) {

            if (side in sides === false) {

            var values = this.getValueSequence(declaration, 1);

            if (!values || !values.length) {

            // can mix only if specials are equal

                if (sides[key] !== null && sides[key].special !== values[0].special) {

  "description": "CSS minifier with structural optimisations",

  "homepage": "https://github.com/css/csso",

  "author": "Sergey Kryzhanovsky <skryzhanovsky@ya.ru> (https://github.com/afelix)",

    "url": "https://github.com/css/csso/issues"

    "lint-and-test": "npm run lint && npm test",

    "build": "rollup --config && terser dist/csso.js --compress --mangle -o dist/csso.min.js",

    "coveralls": "nyc report --reporter=text-lcov | coveralls",

    "travis": "nyc npm run lint-and-test && npm run coveralls",

    "hydrogen": "node --trace-hydrogen --trace-phase=Z --trace-deopt --code-comments --hydrogen-track-positions --redirect-code-traces --redirect-code-traces-to=code.asm --trace_hydrogen_file=code.cfg --print-opt-code bin/csso --stat -o /dev/null",

    "css-tree": "css-tree/dist/csstree.min.js"

    "@rollup/plugin-commonjs": "^11.0.1",

    "@rollup/plugin-node-resolve": "^7.0.0",

		@@ -0,1 +1,7 @@
		## 4.2.0 (November 26, 2020)

		- Trim Custom Property values when possible (#393)
		- Fixed removing unit for zero-length dimentions in `min()`, `max()` and `clamp()` functions (#426)
		- Fixed crash on bad value in TRBL declaration value (#412)

		## 4.1.1 (November 15, 2020)
		@@ -2,0 +8,0 @@

+var packNumber = require('./Number').pack;
+var MATH_FUNCTIONS = {
+    'calc': true,
+    'min': true,
+    'max': true,
+    'clamp': true
+};
+var LENGTH_UNIT = {
+@@ -46,3 +52,3 @@ // absolute length units
+        // issue #222: don't remove units inside calc
+        if (this.function && this.function.name === 'calc') {
+        if (this.function && MATH_FUNCTIONS.hasOwnProperty(this.function.name)) {
+            return;
+@@ -49,0 +55,0 @@ }

		@@ -81,3 +81,3 @@ var List = require('css-tree').List;
		var iehack = '';
		var hasBadValues = declaration.value.children.some(function(child) {
		var hasBadValues = declaration.value.type !== 'Value' \|\| declaration.value.children.some(function(child) {
		var special = false;
		@@ -84,0 +84,0 @@

		{
		"name": "csso",
		"version": "4.1.1",
		"version": "4.2.0",
		"description": "CSS minifier with structural optimisations",
		@@ -41,3 +41,3 @@ "homepage": "https://github.com/css/csso",
		"dependencies": {
		"css-tree": "^1.0.0"
		"css-tree": "^1.1.2"
		},
		@@ -44,0 +44,0 @@ "browser": {

Fixed alerts

Improved metrics

Dependency changes

		@@ -0,5 +1,14 @@
		var property = require('css-tree').property;

		module.exports = function cleanDeclartion(node, item, list) {
		if (node.value.children && node.value.children.isEmpty()) {
		list.remove(item);
		return;
		}

		if (property(node.property).custom) {
		if (/\S/.test(node.value.value)) {
		node.value.value = node.value.value.trim();
		}
		}
		};