How To Reduce Unused JavaScript: Everything You Need To Know

Hello everyone! Wayne here and today I want to go over how reduce unused JavaScriptThis is a great technique for increase PageSpeed and loads times throughout a website.

Reducing unused JavaScript is one of the many great techniques for increasing PageSpeed. Increasing PageSpeed is essential for mastering SEO, rising in Google ranking, and creating an overall more enjoyable experience for website visitors.

Let’s jump on in and discuss everything you need to know about reducing unused JavaScript, and breakdown how to get it done.

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Introduction To Unused JavaScript

Introduction to JavaScript

The PageSpeed on your website could be decreased on all of your web pages by data and files you don’t even know exist. This is typically caused by unused JavaScript and CSS Files.

Google PageSpeed Insights  recommends removing unused JavaScript and CSS Files when rating the PageSpeed of a web page. So this is a PageSpeed tip you’ll definitely want to know all about.

Let’s discuss what JavaScript files are, why there is unused data, and why you should delete or reduce unused JavaScript data

This might sound like a small step towards increasing PageSpeed, but this is one of the techniques that can set you above other websites that don’t go through the trouble of limiting this unused data. This is what can set your website apart from other competing sites with high PageSpeed.

What Are JavaScript Files?

What are Unused JavaScript Files?
JS (JavaScript) files are text files that contain JavaScript code. These files are embed within a webpage and are configured to run and execute coded instructions when a webpage is loaded. 
 

What Are Unused JavaScript Files?

While most JavaScript is completely appropriate and necessary to run your webpage, there are often unused JavaScript files hiding within the code of a webpage. 

This unused JavaScript is typically filler and unnecessary for your webpage to load and run. In fact, it can possibly harm and slowdown PageSpeed.

Why Reduce Unused JavaScript Files?

Unused JavaScript are typically useless and can only slow down your website and stall the web page loading process.

This is why it is beneficial to examine your website and locate unused JavaScript files that may be slowing down your website.

You’ll want to be careful when removing unused JavaScript however, as while most of the time these files are useless, sometimes removing them can mess up a web page. It is important to practice this step in a staging environment.

Let’s break down the process of locating and removing unused JavaScript Files.

How To Find Unused JavaScript Files

Google PageSpeed Insights Unused JavaScript and CSS Files

Finding unused JavaScript files can be tricky at first, but fortunately there are some helpful tools out there that can assist with highlighting unused code.

The Coverage tab in Google DevTools can assist with discovering unused JavaScript Files.

  1. Go to the web page you want to investigate
  2. Open the coverage tab in Google DevTools can assist with discovering unused JavaScript Files
  3. Filter the list to show only JavaScript code
  4. Filter for unused bytes
  5. Inspect the code for unused JavaScript files

After following the above instructions, you should be able to see all of the various unused JavaScript files on your website. However, you’ll want to now use a plugin to reduce or remove the files.

How To Reduce Unused JavaScript Files

How To Reduce Unused JavaScript Files

There are two primary methods for reducing unused JavaScript from A WordPress website. Both of these methods are done by utilizing a plugin.

Method 1: Premium WordPress Plugin
  1. Access the WordPress toolbar
  2. Select “Plugins” on the WordPress Sidebar
  3. Search for and select WP Rocket
  4. Access Rocket WP from the WordPress sidebar
  5. Configure the plugin to reduce unused JavaScript files

WP Rocket is a great plugin because it does all of the complicated work for you. Additionally, WP Rocket has other functionalities that help with PageSpeed. It doesn’t end with just reducing unused JavaScript files. So be sure to explore the other options WP Rocket has to offer.

Method 2: Free WordPress Plugin
  1. Access the WordPress toolbar
  2. Select “Plugins” on the WordPress Sidebar
  3. Search for and select Asset Cleanup
  4. Access Asset Cleanup from the WordPress sidebar
  5. Configure the plugin to reduce unused JavaScript files and delete unused CSS files

Using a free plugin like Asset Cleanup can definitely get the job done, but there are typically limitations.

These limitations include how much or how often you can reduce unused code, and whether or not the plugin can only reduce unused code, not remove it entirely.

You’ll have to upgrade to Asset Cleanup Pro or another premium plugin if you want to fully remove unused code.

*Note: While you can use multiple optimization plugins at once, be sure that none of your plugins have overlap. For example: If WP Rocket is being used to reduce unused JavaScript files, make sure no other plugin is configured to perform that same task.

Reducing Unused JavaScript Tips

Unused JavaScript Files Tips
Here are some helpful tips for reducing unused JavaScript files
  • Use WordPress plugins to easily reduce unused JavaScript files
  • Ensure there is no over lapped configurations amongst installed plugins
  • Frequently check for unused JavaScript files on your website
  • Use free plugins if you have a new website and want to limit expenses
  • Reduce unused CSS files to maximize PageSpeed benefits
Now I want to spend some time answering frequently asked questions regarding reducing unused JavaScript files.
 

Reducing Unused JavaScript FAQ

Unused JavaScript Files FAQ

Why Are There Unused JavaScript Files?

While JavaScript files are often helpful and essential for a website to function, there is often non-critical or redundant JavaScript files that are not necessary for a website to function perfectly. This is exactly the type of JavaScript files you want to reduce. This is unnecessary code that typically isn’t even loaded into the website. 

How Does Reducing Unused JavaScript Files Increase PageSpeed?

Reducing unused JavaScript files is great for PageSpeed because this non-critical data takes up valuable bandwidth on a website. By removing this redundant and non-critical data, you can increase the PageSpeed on a website. I highly recommend you read my guide on how to increase PageSpeed if you want to know everything there is to know about PageSpeed.

Why Does PageSpeed Matter?

 PageSpeed is an important factor both for increasing the SEO of your website as well as improving the quality and experience of it. No one wants to wait several seconds for web page to load, especially these days. There are other websites that are going to load nearly instantly, so if your website is slow you will lose visitors. Google knows this too, and that is why slow websites often have poor SEO.

What Are CSS Files?

CSS (Cascading Style Sheets) are files that describe how HTML or XML elements are displayed on the webpage. These files describe everything from the layout to the style of the contents of the webpage. These files are important for displaying any webpage, but unused and extraneous CSS files can be an issue. Just like with unused JavaScript files, having unused CSS files can slow down the loading speed of your page and decrease PageSpeed.

How Do You Reduce Unused CSS Files?

The process of removing unused CSS files is very similar to how you go about removing unused JavaScript files. The only difference is selecting the appropriate toggles and options for reducing unused CSS files as well. For more information about this process I highly recommend you check out my article on reducing unused CSS files.

Reducing Unused JavaScript Resources

WP Rocket

Here are some helpful resources for reducing unused JavaScript:

WP Rocket

WP Rocket is one of the best plugins for reducing unused JavaScript. The plugin has premium options that make reducing unused JavaScript easy and efficient. Additionally, WP Rocket has other functionalities that help with PageSpeed. It doesn’t end with just reducing unused JavaScript files. So be sure to explore the other options WP Rocket has to offer.

Asset Cleanup

Asset Cleanup is a great free alternative to WP Rocket. This plugin is perfect for those who want to save money and aren’t too serious about investing into the PageSpeed of their website. While I highly recommend any professional blogger takes PageSpeed seriously, it is perfectly reasonable to take your time with website optimization.

Asset Cleanup is a free alternative, but it comes with limitations. These limitations include how much or how often you can reduce unused code, and whether or not the plugin can only reduce unused code, not remove it entirely. You’ll have to upgrade to Asset Cleanup Pro or switch to another premium plugin if you want to fully remove unused code.

*Note: While you can use multiple optimization plugins at once, be sure that none of your plugins have overlap. For example: If WP Rocket is being used to reduce unused JavaScript files, make sure no other plugin is configured to perform that same task.

Other Ways To Increase PageSpeed

PageSpeed

If you are interesting in reducing unused JavaScript and increasing load times, I would take a bet that you might be interested in some additional tips for increasing PageSpeed. Here is a list of other tips for increasing PageSpeed:

Other Techniques For Increasing PageSpeed:

Each of these factors are an opportunity to increase the PageSpeed on your website. Click on any of the individual PageSpeed techniques above if you want to learn more about it

If you want to learn everything there is to know about PageSpeed, I highly recommend you check out my how to increase PageSpeed guide!

In this guide, I go in to full detail over nine of the most essential tips for increasing PageSpeed across a website. This is a huge article, but it is worth adventuring through I promise.

PageSpeed Tips & Tricks

PageSpeed Insights

Here is a roundup of all the tips for increasing PageSpeed that will have your website running fast and efficiently.

Tips & Tricks For Increasing PageSpeed:
  • Self-host your blog through a web host (BlueHost)
  • Use a fast WordPress Theme (Themify Ultra)
  • Don’t enable ads as a new website
  • Optimize the images on the website
  • Install less than 10 plugins in total
  • Use more techniques for increasing PageSpeed such as optimizing images, reducing unused JavaScript and CSS files, and more
  • Convert images on the website to WebP format
  • Keep your website simple, don’t over-do the graphics
There is a lot more that goes into increasing PageSpeed across a website. If you want to know more about how to get backlinks, I recommend you check out my full guide on How To Increase PageSpeed.
 

Related Content

Reducing unused JavaScript is just one of the many techniques for increasing PageSpeed. Fortunately, I have more content on my website that can help you master PageSpeed.

I highly recommend you explore some of these other great articles from my website to learn more about what goes into running a successful and healthy blog.

Here is some related content that can help you increase the PageSpeed of your website.

How To Increase PageSpeed

How To Increase PageSpeed
If you want a fast website, I recommend reading through my article on How To Increase PageSpeed.

In this guide I go over nine tips that can get your website a highly respectable 97/100 PageSpeed score from Google PageSpeed Insights. So if you want to know everything there is to know about increasing PageSpeed, I highly recommend reading through this guide.

How To Optimize Images

How To Optimize Images
Reducing unused JavaScript is only one of the many ways to increase the PageSpeed of a website. Another great technique is to optimize the images on the site. If this sounds interesting to you, I recommend you check out my article on How To Optimize Images.

In this article I go over two of the primary techniques for optimizing images. I also share all of the tips & tricks I use for my own website.

So if you want to learn all about image optimization, I highly recommend you give this guide a read through.

Closing Thoughts

That’s everything you need to know on how to reduce unused JavaScript! I hope this guide was helpful, and I wish you the best of success your blogging career.

Please feel free to reach out to me or comment down below if you have any questions or need any additional guidance. Also feel free to share your own blogging tips as well! I always appreciate an opportunity to learn more. See you next time!