FullHuman/purgecss
Purgecss
PurgeCSS is a build-pipeline CSS purger and optimizer designed to reduce the final size of stylesheets. It functions as a tree shaking tool that scans HTML and JavaScript files to identify and remove unused selectors from CSS.
The tool optimizes CSS payloads by performing static content analysis to detect which styles are actually used in the markup. It uses regex-based pattern matching to find potential class names without executing code and employs a PostCSS-based AST transformation to safely delete unused rules.
The project provides capabilities for frontend build automation, allowing the removal of unused styles to be integrated directly into module bundlers and task runners. It also includes a custom-whitelist filter to preserve essential selectors regardless of whether they are detected during the content scan.
Features
- CSS Selector Purging - Removes CSS rules whose selectors do not match any elements found during the static content scan.
- Content Pattern Matching - Uses regex-based pattern matching to identify potential CSS class names within HTML and JavaScript files.
- CSS AST Transformations - Employs a PostCSS-based AST transformation to safely remove unused rules from the stylesheet structure.
- Markup Usage Analysis - Scans HTML and JavaScript files to create a comprehensive list of all CSS selectors used in the markup.
- CSS Payload Reduction - Reduces the total byte size of delivered CSS by purging redundant and unused rules.
- CSS Unused Style Removers - Automates the removal of unused styles by integrating with module bundlers and task runners.
- CSS Build Tools - Acts as a build-time engine that scans source files to optimize and compile CSS styles.
- Frontend Build Toolchains - Integrates style cleanup directly into the frontend build toolchain for automated deployment.
- Build Tool Integrations - Integrates directly as an extension within common build systems to automate stylesheet optimization.
- CSS Selector Whitelists - Provides a whitelist filter to ensure essential CSS selectors are preserved regardless of content analysis.
- Web Performance Tuning - Eliminates dead CSS code to decrease browser rendering time and minimize data transfer.
- CSS Optimization - Remove unused CSS to reduce file size.
