CSS Debugging and Optimization: Code-quality Tools

Improving the quality of CSS code: Detailed explanation of stylelint and UnCSS tools

Core points

stylelint and UnCSS are two practical tools for analyzing the quality of CSS code. stylelint checks for potential problems in the code, such as forcing spaces instead of tabs for indentation; UnCSS detects and removes unused selectors and style rules. Both tools are based on Node.js and can be installed using npm. For small websites, many tool tagging issues can be ignored, but for large projects, they help prevent maintenance issues. Task runners or build systems such as Grunt, Gulp, and webpack can automate connections and optimize tasks, reducing the amount of work used by tools such as stylelint and UnCSS. These tools can be integrated with Grunt, Gulp, or webpack through plugins. CSS debugging and optimizing code quality tools can improve website loading speeds, which is crucial because slow loading websites can lead to poor user experience and negatively affect the search engine ranking of the website. (The following introduction to CSS code quality tools is excerpted from Tiffany's new book "CSS Master, Second Edition")

On the road to becoming a CSS master, you need to understand how to debug and optimize CSS code. How to diagnose and fix rendering issues? How do I make sure your CSS doesn't cause performance lag for end users? And how to ensure the quality of the code?

It is crucial to understand which tools can help you ensure that the front-end is running properly.

In this article, we will discuss some tools for analyzing the quality of CSS code. We will focus on the following two tools:

stylelint UnCSS stylelint is a code style checking tool (linter). Linter is an application that checks for potential problems in code, which enforces code conventions, such as indentation using spaces instead of tabs. stylelint can find problems such as repeat selectors, invalid rules, or unnecessary specificity. These issues have the greatest impact on the maintainability of CSS.

On the other hand, UnCSS checks for unused selectors and style rules in CSS. It parses the stylesheet and HTML page list, returning a CSS file with unused rules removed.

Both tools use Node.js and can be installed using npm.

If you are dealing with small websites (such as personal blogs or some pages with infrequent updates), you can safely ignore many of the issues tagged by these tools. You will spend time refactoring, but with little success in maintainability and speed. However, for large projects, they are invaluable. They will help you avoid maintainability issues before the problem begins.

stylelint stylelint helps you avoid errors and enforce conventions in styles. It has over 160 error checking rules and allows you to create your own rules through plugins.

stylelint installation and configuration Install stylelint like any other npm package:

npm install -g stylelint After the installation is complete, we need to configure it before using stylelint. stylelint does not come with a default configuration file. We need to create a configuration file. Create a .stylelistrc file in the project directory. This file will contain our configuration rules, which can be used with JSON (JavaScript object notation) or YAML (YAML Ain't Markup Language) syntax. The examples in this section use JSON.

Our .stylelistrc file must contain an object with rules attribute. The value of rules will itself be an object that contains a set of stylelint rules and their values:

{ "rules": {} } For example, if we want to disable the !important declaration, we can set declaration-no-important to true :

{ "rules": { "declaration-no-important": true } } stylelint supports more than 150 rules that check for syntax errors, indentation and newline consistency, invalid rules and selector specificity. You can find a complete list of rules and their available values in the stylelint user guide.

Start with the basic stylelint configuration You may find it easier to start with the basic configuration and then customize according to the project requirements. stylelint-config-recommended The basic configuration is a good starting configuration. It enables all "possible errors" rules. Install it using npm:

npm install -g stylelint-config-recommended Then, in your project directory, create a .stylelistrc file with the following lines:

{ "extends": "/absolute/path/to/stylelint-config-recommended" } Replace /absolute/path/to/ with the directory where you installed stylelint-config-recommended . Global npm packages are usually found in the %AppData%\npm\node_modules directory of Windows 10 systems, and in Unix/Linux and macOS systems. Type /usr/local/lib/node_modules to find your global npm list -g directory. node_modules

We can then enhance our configuration by adding attributes. For example, to ban vendor prefixes, our rules file will look like the following: .stylelistrc

{ "extends": "/absolute/path/to/stylelint-config-recommended", "rules": { "value-no-vendor-prefix": true } } What if we want to limit the maximum specificity of the selector to 0,2,0? This will allow selectors like , but not .sidebar .title . We can do this by adding the #footer_nav rules to our configuration: selector-max-specificity

{ "extends": "/absolute/path/to/stylelint-config-recommended", "rules": { "value-no-vendor-prefix": true, "selector-max-specificity": "0,2,0" } } Use stylelint To use stylelint to check CSS files, run the stylelint command and pass the path to the CSS file as a parameter:

stylelint stylesheet.css Alternatively, you can check all CSS files in a specific directory, or even recursively check:

stylelint "./css/**/*.css" stylelint can also use the element to check CSS embedded in HTML files. Just pass the path to the HTML file as a parameter. style

When finished, stylelint will display a list of files containing the errors, as shown in the image below.

UnCSS UnCSS parses your HTML and CSS files, deleting unused CSS. If your project contains a CSS framework like Bootstrap or uses a reset stylesheet, consider adding UnCSS to your workflow. It will remove unnecessary CSS and bytes from your code.

UnCSS installation Like other npm packages, you can install UnCSS with the following command:

npm install -g stylelint Use UnCSS from the command line UnCSS requires the file path or URL of the HTML page containing the linked CSS file. For example:

{ "rules": {} } UnCSS will parse HTML and its linked stylesheets and print the optimized CSS to standard output. To redirect to a file, use the redirect operator ( > ):

{ "rules": { "declaration-no-important": true } } You can also pass multiple file paths or URLs to the command line. UnCSS analyzes each file and dumps the optimized CSS with rules affecting one or more pages:

npm install -g stylelint-config-recommended See the UnCSS documentation for a complete list of commands and an example of how to use UnCSS using Node.js scripts.

Consider using a task runner or build tool Running these tools may seem like a lot of extra work. To do this, consider adding a task runner or build system to your workflow. Popular task runners include Grunt, Gulp, and webpack. All three tools have well-documented documentation and a huge developer community.

The advantage of these task runners and build systems is that they can automate connections and optimize tasks. They are not limited to CSS either. Most build tools also include plugins for optimizing JavaScript and images.

Because configuration and build script files are usually JSON and JavaScript, you can easily reuse them between projects or share them with your team. Each tool mentioned in this article can be integrated with Grunt, Gulp, or webpack through plugins.

Most importantly, take a pragmatic approach to building your toolkit. Add tools you think can enhance your workflow and improve output quality.

(To learn more about CSS debugging and optimization, please check out Tiffany's book "CSS Master, Second Edition")

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CSS debugging and optimization: browser-based developer tools CSS debugging and optimization: compression using CSSO FAQs (FAQs) about CSS debugging and optimizing code quality tools What are the benefits of using CSS debugging and optimizing code quality tools? CSS debugging and optimizing code quality tools are essential for any web developer. They help identify and fix bugs in CSS code, ensuring your website works as expected. These tools also help optimize CSS code, which can significantly improve website loading speed. This is crucial because slow loading websites can lead to poor user experience and negatively impact the search engine ranking of the website. Additionally, these tools can help maintain the quality of CSS code, making it easier to read and manage.

How does UnCSS work? UnCSS is a powerful tool that analyzes your HTML and CSS files to remove unused styles. It works by parsing HTML files, identifying the CSS selectors used, and then comparing them to the selectors in the CSS file. Any selectors in the CSS file that are not used in the HTML file are considered unused and will be deleted. This can significantly reduce the size of the CSS file, thus speeding up the loading of the website.

How to use UnCSS online? UnCSS Online is a web-based tool that allows you to use UnCSS without installing it on your computer. To use it, simply visit the UnCSS online website, paste your HTML and CSS code into the provided field, and click the "Delete Unused CSS" button. The tool will then analyze your code and give you a new CSS file that contains only the styles used in the HTML code.

Video tutorial on how to use UnCSS? Yes, there are many video tutorials online that can guide you on how to use UnCSS. These tutorials provide step-by-step instructions that are easy for even beginners to understand and use the tool. There are tutorials like this on YouTube.

How to remove unused CSS from my website? There are several tools and methods to remove unused CSS from your website. One of the most popular tools is UnCSS, which analyzes your HTML and CSS files to remove unused styles. Other tools include PurifyCSS and CSSNano, which also help optimize CSS code. Additionally, you can manually delete unused CSS by using browser developer tools to check your website and identify unused styles.

Are there any other CSS debugging and optimization tools? In addition to UnCSS, there are several other CSS debugging and optimization tools available. These tools include CSS Lint, which helps identify and fix errors in CSS code; CSS Miniifier, which reduces the size of CSS files by removing unnecessary characters; and Autoprefixer, which adds vendor prefixes to CSS to ensure that with Compatibility of different browsers.

How to ensure the quality of CSS code? Ensuring the quality of CSS code involves a variety of practices. These include using CSS preprocessors like Sass or Less, which helps organize code and make it easier to manage; using CSS linter to identify and fix errors; and using CSS optimizer to remove unnecessary characters and optimize code . In addition, following best practices such as using meaningful class and ID names, annotation code, and adhering to a consistent coding style can also help maintain the quality of CSS code.

How does CSS debugging and optimization tools improve SEO of my website? CSS debugging and optimization tools can significantly improve the SEO of your website by increasing the loading speed of your website. Search engines like Google view page loading speed as a ranking factor, so websites that load faster may rank higher in search results. In addition, these tools can help create a better user experience, which will also have a positive impact on the website's SEO.

If I'm a beginner, can I use CSS debugging and optimization tools? Yes, most CSS debugging and optimization tools are designed to be user-friendly and available to beginners and experienced developers. Many of these tools provide detailed documentation and tutorials to get you started. However, it is best to have a certain understanding of CSS before using these tools.

What are the disadvantages of using CSS debugging and optimization tools? While CSS debugging and optimization tools offer many benefits, they also have some potential drawbacks. For example, some tools may remove styles that are not currently used but may be required in the future. Additionally, these tools may sometimes generate false positives, identifying styles as unused when in fact they are needed. Therefore, be sure to double-check these changes before applying them to your website.