clean-css VS clean-css-cli

Minification involves removing unnecessary characters, whitespace, and comments from code files. It helps reduce HTML, CSS, JavaScript, etc., file sizes without compromising functionality. Removing redundant elements makes these HTML, JavaScript, and CSS files smaller. Since smaller code files need less internet traffic to transfer, they load faster. Utilizing tools like UglifyJS, Clean-CSS, and HTMLMinifier enhances this process of code reduction. They analyze the code, remove redundant code, and generate optimized files for deployment.

By setting minifyCSS and minifyJS to true, the CSS will be minified together using clean-css and the JS will be minified together using UglifyJS to minify the JS together. Also, the other side of gatsby-plugin-minify is just multiplying html-minifier by postbuild in gatsby-node.js. You can set detailed options in html-minifier.

Depending on whether set to true or false (or not included as the default value is false), the last two options, --minify-js and --minify-css will minify the corresponding source of their type, only if included as inline style or script tags in the html being minified. It may also be good to know that the html-minifier options information states that clean-css and uglify-js are used for the minification when these options are included.

Similar to the compile-styles script, the css-minify script is also quite long and contains many parameters. More info on all the parameters can be found at the clean-css-cli GitHub repo. The parameters being passed in indicate to run clean-css with a certain level of optimization, line break formatting, and to include source maps with the optimized output. The file to optimize is the styles.css file located in the dist folder that was generated by the compile-styles command, and the optimized output will be written to styles.min.css in the same folder. Now that all the required scripts have been added to the package.json file we can first compile, and then minify the scss source, by running the command npm run compile-styles followed by the command npm run css-minify. Then looking in the dist folder that was created there should be four files: