How to remove redundant css

In the process of web development, multiple developers and the passage of time often lead to the accumulation of a large number of redundant styles in CSS files, which is the so-called "junk CSS". These junk CSS will cause the website to become extremely large and complex, reduce performance and maintainability, and also increase development costs. Therefore, in some large projects, cleaning up redundant CSS has become a serious problem that must be solved.

So how to clean up redundant CSS? Here, I will share some methods and tools to solve this problem:

1. Manual Cleaning

Manual cleaning is the most original and basic method. By carefully looking at your CSS files and removing redundant and unused styles, you can achieve considerable optimization results. However, the shortcomings of this method are also obvious. The operation is time-consuming and labor-intensive, requires extreme patience and care, and is prone to omissions and errors. Therefore, this method is suitable for smaller projects and simple pages.

2. Code analysis tool

The code analysis tool can help us automatically find junk CSS code, making it easy to quickly find and delete redundant styles. Commonly used tools are:

(1) Google Chrome DevTools

Chrome DevTools is a tool that comes with the Chrome browser. Through the Coverage analysis function, you can find unused CSS code in the web page and delete it. . The specific operation method is as follows:

• Open Chrome DevTools
• Select the Coverage tab
• Click the "Start Recording" button and wait for the website to load
• Stop recording and view unused CSS code

Advantages: Simple and easy to use, no need to install other software.

(2) PurifyCSS

PurifyCSS is a command line tool that can extract used styles from HTML and CSS files and generate a new CSS file. The specific operation method is as follows:

• Install PurifyCSS: npm install purify-css
• Use PurifyCSS command: purifycss [input.css] [content.html] -o [output.css]

Advantages: Can automatically process a large number of CSS files.

3. Automation tools

Automation tools are a more powerful and efficient way that can achieve automatic cleaning through some scripts. Commonly used tools are:

(1) Grunt

Grunt is a JavaScript-based task runner that can automatically process CSS, JavaScript, images and other resources through some plug-ins. Redundant CSS can be cleaned up by using the grunt-uncss plugin. The specific operation method is as follows:

• Install Grunt: npm install -g grunt-cli
• Go to the root directory of the project and create a new file named Gruntfile.js
• Configure the Gruntfile.js file and add how to use the grunt-uncss plug-in
• Execute the grunt command to run the Grunt task

Advantages: Multiple functions can be achieved through a series of tasks , extremely flexible and scalable.

(2) Gulp

Gulp is a flow-based automated build tool that can also automatically clean CSS through some plug-ins. Cleaning up redundant CSS can be achieved by using the gulp-uncss plugin. The specific operation method is as follows:

• Install Gulp: npm install -g gulp-cli
• Create a new project and enter the project root directory
• Install gulp-uncss Plug-in: npm install --save-dev gulp-uncss
• Add related tasks in the gulpfile.js file
• Use the gulp command to run the task

Advantages: Data can be processed in a streaming manner, which is fast and can handle large amounts of files efficiently.

To sum up, there are many methods and tools to choose from to remove redundant CSS. The specific method chosen depends on the size and complexity of the project and the developer's habits and preferences. But overall, cleaning up redundant CSS is a very beneficial thing to do and can greatly improve the performance and maintainability of your website.

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