JavaScript is another render-blocking resource that is a great candidate for minification. Just like CSS or HTML, JavaScript can become bloated and unnecessarily large due to comments, white spaces, repeating code, etc. This causes the browser to require more time to download and render JavaScript code. We discussed avoiding main-thread tasks earlier in this guide and minifying JavaScript can help reduce the time it takes for the main-thread work to process. Again, keeping files as small as possible has a direct effect on how fast the browser can download, parse, and execute them.
JavaScript is a bit different in that minification by itself does not offer significant performance benefits, but done in conjunction with CSS and HTML minification, as well as other optimization techniques, such as caching, it is another method to improve overall page load times. Additionally, JavaScript minification must be done carefully as complicated scripts could be ruined or potentially introduce bugs in the code that could have unintended consequences.
