analyze-css：CSS选择器的复杂度和性能分析器_html/css_WEB-ITnose

analyze-css

CSS selectors complexity and performance analyzer. analyze-css is built as a set of rules bound to events fired by CSS parser. Each rule can generate metrics and add "offenders" with more detailed information (see Usage section for an example).

Analyze CSS Demo

Install

analyze-css comes as a "binary" for command-line and as CommonJS module. Run the following to install them globally:

npm install --global analyze-css 

Usage

Command line tool

You can use analyze-css "binary" to analyze local CSS files or remote CSS assets:

analyze-css --file examples/elecena.cssanalyze-css --url http://jigsaw.w3.org/css-validator/style/base.css 

You can provide CSS via stdin as well (notice the dash: -):

echo ".foo {margin: 0 \!important}" | analyze-css - 

This will emit JSON formatted results on stdout. Use --pretty (or -p shortcut) option to make the output readable for human beings.

Basic HTTP authentication can be provided through the options --auth-user and --auth-pass.

CommonJS module

var analyzer = require('analyze-css');new analyzer('.foo {margin: 0 !important}', function(err, results) {  console.error(err);  console.log(results); // example? see below}); 

// options can be providedvar opts = {  'noOffenders': true};new analyzer('.foo {margin: 0 !important}', opts, function(err, results) {  console.error(err);  console.log(results); // example? see below});``` 

grunt task

Created by @DeuxHuitHuit

npm i grunt-contrib-analyze-css 

It uses configurable threshold and compares the analyze-css result with it.

Results

{  "generator": "analyze-css v0.8.0",  "metrics": {    "base64Length": 11332,    "redundantBodySelectors": 0,    "redundantChildNodesSelectors": 1,    "colors": 106,    "comments": 1,    "commentsLength": 68,    "complexSelectors": 37,    "complexSelectorsByAttribute": 3,    "duplicatedSelectors": 7,    "duplicatedProperties": 24,    "emptyRules": 0,    "expressions": 0,    "oldIEFixes": 51,    "imports": 0,    "importants": 3,    "mediaQueries": 0,    "multiClassesSelectors": 74,    "parsingErrors": 0,    "oldPropertyPrefixes": 79,    "propertyResets": 0,    "qualifiedSelectors": 28,    "specificityIdAvg": 0.04,    "specificityIdTotal": 25,    "specificityClassAvg": 1.27,    "specificityClassTotal": 904,    "specificityTagAvg": 0.79,    "specificityTagTotal": 562,    "selectors": 712,    "selectorLengthAvg": 1.5722460658082975,    "selectorsByAttribute": 92,    "selectorsByClass": 600,    "selectorsById": 25,    "selectorsByPseudo": 167,    "selectorsByTag": 533,    "universalSelectors": 5,    "length": 55173,    "rules": 433,    "declarations": 1288  },  "offenders": {    "importants": [      ".foo {margin: 0 !important}"    ]  }} 

Metrics

base64Length : total length of base64-encoded data in CSS source (will warn about base64-encoded data bigger than 4 kB) redundantBodySelectors : number of redundant body selectors (e.g. body .foo, section body h2, but not body > h1) redundantChildNodesSelectors : number of redundant child nodes selectors (e.g. ul li, table tr) colors : number of unique colors used in CSS comments : number of comments in CSS source commentsLength : length of comments content in CSS source complexSelectors : number of complex selectors (consisting of more than three expressions, e.g. header ul li .foo) complexSelectorsByAttribute : number of selectors with complex matching by attribute (e.g. [class$="foo"]) duplicatedSelectors : number of CSS selectors defined more than once in CSS source duplicatedProperties : number of CSS property definitions duplicated within a selector emptyRules : number of rules with no properties (e.g. .foo { }) expressions : number of rules with CSS expressions (e.g. expression( document.body.clientWidth > 600 ? "600px" : "auto" )) oldIEFixes : number of fixes for old versions of Internet Explorer (e.g. * html .foo {} and .foo { *zoom: 1 }, read more) imports number of @import rules importants : number of properties with value forced by !important mediaQueries : number of media queries (e.g. @media screen and (min-width: 1370px)) multiClassesSelectors : reports selectors with multiple classes (e.g. span.foo.bar) parsingErrors : number of CSS parsing errors oldPropertyPrefixes : number of properties with no longer needed vendor prefix, powered by data provided by autoprefixer (e.g. --moz-border-radius) propertyResets : number of accidental property resets qualifiedSelectors : number of qualified selectors (e.g. header#nav, .foo#bar, h1.title) specificityIdAvg : average specificity for ID specificityIdTotal : total specificity for ID specificityClassAvg : average specificity for class, pseudo-class or attribute specificityClassTotal : total specificity for class, pseudo-class or attribute specificityTagAvg : average specificity for element specificityTagTotal : total specificity for element selectors : number of selectors (e.g. .foo, .bar { color: red } is counted as two selectors - .foo and .bar) selectorLengthAvg : average length of selector (e.g. for .foo .bar, #test div > span { color: red } will be set as 2.5) selectorsByAttribute : number of selectors by attribute (e.g. .foo[value=bar]) selectorsByClass : number of selectors by class selectorsById : number of selectors by ID selectorsByPseudo : number of pseudo-selectors (e,g. :hover) selectorsByTag : number of selectors by tag name universalSelectors : number of selectors trying to match every element (e.g. .foo > *) length : length of CSS source (in bytes) rules : number of rules (e.g. .foo, .bar { color: red } is counted as one rule) declarations : number of declarations (e.g. .foo, .bar { color: red } is counted as one declaration - color: red)

Read more

Writing Efficient CSS (by Mozilla) Optimize browser rendering (by Google) Profiling CSS for fun and profit. Optimization notes. CSS specificity CSS Selector Performance has changed! (For the better) (by Nicole Sullivan) CSS Performance (by Paul Irish) GitHub's CSS Performance (by Joh Rohan)

Dev hints

Running tests and linting the code:

npm test && npm run-script lint 

Turning on debug mode (i.e. verbose logging to stderr via debug module):

DEBUG=analyze-css* analyze-css ... 

项目地址： https://github.com/macbre/analyze-css

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