Detailed explanation of the POSTCSS framework technical principle in the Java class library

PostCSS is a tool for converting CSS. It is based on JavaScript and uses a plug -in system.It is designed to expand and transform CSS through JavaScript code, enabling developers to customize and optimize CSS through programming. The working principle of postcss is as follows: 1. Analysis: PostCSS first analyzes the input CSS code to an abstract syntax tree (AST), which converts the CSS code into a data structure that can be understood and operated by the program.This process uses the CSS-PARSER library. 2. Plug -in processing: PostCSS processs CSS through the plug -in system.Each plugin can process CSS AST and generate corresponding output.The plug -in can be used for various purposes, such as adding browser prefixes, compressing CSS code, and conversion of new CSS syntax. 3. Conversion: After processing the plug -in, PostCSS will traverse the entire AST, and the corresponding conversion is based on the configuration and rules of the plug -in.These conversions can modify any aspects of CSS, such as attributes, selectors, rules, etc. 4. Generate output: Finally, PostCSS re -generates the conversion AST into a CSS code, which can be saved in the file or directly injected into the HTML page. Below is an example configuration file using postcss: script const postcss = require('postcss'); const autoprefixer = require('autoprefixer'); const css = ` body { display: flex; justify-content: center; align-items: center; } `; postcss([autoprefixer]) .process(css) .then(result => { console.log(result.css); }); In the above example, we first introduced the `Postcss` and` Autoprefixer` plug -in.Then we define a CSS code string.Next, we use the `Postcss` function to create a postcss processor and pass the` Autoprefixer` plug -in as a parameter to it.Finally, we use the `.Process` method to process the CSS code and print the result through the` .Then` callback function. Through the above configuration files, we can automatically add an appropriate browser prefix to the CSS code.This is because the `Autoprefixer` plug -in will detect the attributes in the CSS rule and automatically add the required browser prefix according to the configuration. In summary, PostCSS is a powerful CSS processing tool that can expand and conversion to CSS through the plug -in system.Its working principles include analysis, plug -in processing, conversion, and generating output steps.By writing a custom plug -in, developers can optimize and customize CSS according to their needs.