How to Remove Unused JavaScript from Your Website

This article explains how to remove unused JavaScript to optimise your website effectively.

Removing unused JavaScript is essential to improve your website’s loading speed and overall performance.

Why Remove Unused JavaScript?

Unused JavaScript enhances page load time, negatively affecting user experience and search engine rankings. By eliminating it, you can:

1. Reduce page size.
2. Improve loading speed.
3. Enhance Core Web Vitals, particularly First Input Delay (FID) and Total Blocking Time (TBT) scores.

Steps to Remove Unused JavaScript:

Step 1: Analyse Your Website
Use tools like Google PageSpeed Insights, Lighthouse, or WebPageTest to identify unused JavaScript.

1. Enter your website URL in the tool.
   
2. Check the Diagnostics or Opportunities section for “Remove unused JavaScript.”
3. Note down the scripts flagged as unused.

Step 2: Decrease and Combine JavaScript Files

1. Use tools like UglifyJS, Terser, or Webpack to minify and combine JavaScript files.
2. This reduces file size and helps remove redundancy.

Step 3: Defer or Async JavaScript Loading

1. Add the defer attribute to non-essential JavaScript files:

   <script src="example.js" defer></script>

2. Use the async attribute for JavaScript that can load independently of other scripts:

   <script src="example.js" async></script>

Step 4: Eliminate Needless JavaScript

1. Manually Remove Code: Classify unused code in your custom scripts and remove it from your source files.
2. Disable Unused Plugins: Deactivate or delete WordPress plugins that add pointless JavaScript.

Step 5: Use a Code Splitting Tool
Use tools like Webpack or Parcel for code splitting to load only the necessary JavaScript on specific pages.

Step 6: Implement Lazy Loading
Lazy load JavaScript so it only executes when required. Libraries like Lazysizes or plugins like WP Rocket can help with lazy loading.

Step 7: Optimise Third-Party Scripts

1. Remove needless third-party integrations like unused analytics or marketing scripts.
2. Use tools like Google Tag Manager to control which scripts load on specific pages.

Step 8: Test Your Changes

1. After optimizing, re-analyze your site using Google PageSpeed Insights or Lighthouse.
2. Ensure there are no functionality issues or broken scripts.

Tools for Handling Unused JavaScript

1. WordPress Plugins: WP Rocket, Asset CleanUp, or Perfmatters.
2. Browser DevTools: Use the Coverage tab in Chrome DevTools to identify unused JavaScript on specific pages.

Eliminating unused JavaScript can greatly improve your website’s performance, resulting in a better user experience and higher search engine rankings. Continuously monitor and update your scripts to ensure peak efficiency.

Looking to manage your WordPress installation through cPanel? Check out our guide on How to Remove WordPress from cPanel with Softaculous