Reduce Unused JavaScript: Enhancing Your Website Performance

Experienced E-commerce Agency for Magento/ Adobe Commerce/ Shopify/ Shopware Development

Hey there, fellow web enthusiasts!

Are you tired of dealing with slow and heavy websites that take forever to load?

Well, guess what? You’re not the only one here! In this technology-developing world, where users have an attention span shorter than a goldfish, having a lightning-fast website is more essential than ever. And that’s where we come in.

Unused JavaScript is like that extra baggage, the unnecessary code that just sits there, doing nothing except taking up valuable space and causing your website to lag. We’re here to help you shed that dead weight and optimize your code like a pro.

So, if you’re ready to boost your website’s performance and create a speedy user experience, buckle up! It’s time to trim the fat and reduce the unused JavaScript blocking your web projects. Let’s get started and make your website fly!

Table of Contents

What is unused JavaScript?

What is unused JavaScript?

In general, unused JavaScript refers to unexecuted code segments in web applications or websites, often caused by changes in requirements, refactoring, or conditional statements preventing certain code paths from being executed.

Moreover, developers create JavaScript code for web applications, handling functions like form validation, event handling, and DOM manipulation. As the application evolves, modified features may become unused, causing unused code.

Also, unused JavaScript negatively impacts web application performance and efficiency by consuming time and resources in parsing and processing files, resulting in slower page load times and increased resource consumption.

To sum up, unused JavaScript can improve web application performance, maintainability, and efficiency, ensuring seamless user experience and optimal performance in modern web development.

What causes unused JavaScript?

What causes unused JavaScript?

There are several factors that can contribute to unused JavaScript in a web application. Here are some common causes:

  • Code refactoring. The development process involves code changes, including feature additions, modifications, and removals. Incorrect removal of unnecessary functions can result in unused JavaScript.

  • Iterative development. Iterative development gradually adds new features, causing unused older JavaScript code to accumulate and become unutilized over time.

  • Frameworks and libraries. Web applications often use frameworks and libraries for development, potentially containing default code or functionality that can contribute to unused JavaScript if not removed.

  • Conditional code. Conditional statements in JavaScript control code paths, but improper updates or removal can make code portions unused. Properly updated conditions ensure code integrity and maintainability.

  • Dead code elimination. Minification tools remove unused code to reduce file sizes and improve performance, but may not catch all instances, especially dynamically determined at runtime.

  • Legacy code. Unused JavaScript accumulates in large codebases due to changes in requirements, priorities, or deprecated features, affecting long-term projects.

Read more: 12+ Magento Website Maintenance Tips That You Should Implement Now

Why should you remove unused JavaScript from your website?

Why should you remove unused JavaScript from your website?

Removing unused JavaScript from your website offers several benefits:

  • Improved performance. Unused JavaScript increases website file size and loading time. Therefore, removing it reduces data download and processing, improving performance and faster page load times.

  • Bandwidth efficiency. Optimizing JavaScript code reduces data transfer between server and user, especially for limited bandwidth or mobile devices. This ensures efficient bandwidth usage and reduces costs.

  • Enhanced user experience. Improve user experience by removing unused JavaScript, ensuring faster page load times, reducing frustration and abandonment, and improving user experience.

  • Simplified maintenance. Unused JavaScript on websites complicates maintenance and updates. Hence, removing it simplifies the codebase, making it easier to maintain, debug, and enhance future website enhancements.

  • Reduced security risks. Unused JavaScript can introduce security vulnerabilities to your website if not regularly updated or maintained. So, removing unused JavaScript minimizes the attack surface and reduces potential risks.

Overall, removing unused JavaScript is essential in optimizing your website’s performance, enhancing user experience, simplifying maintenance, and reducing security risks. It helps ensure that your website remains efficient, fast, and secure for your visitors.

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How to find unused JavaScript on your website?

Find unused JavaScript by PageSpeed Insights

PageSpeed Insights is a web performance analysis tool provided by Google that can help you identify unused JavaScript on your website. By using PageSpeed Insights, you can optimize website performance by detecting unused JavaScript and providing recommendations.

Find unused JavaScript by PageSpeed Insights

Here’s how you can use PageSpeed Insights to find and reduce unused JavaScript:

  • Step 1: Go to the PageSpeed Insights website and enter the web page URL you want to analyze.

  • Step 2: Click on the Analyze button to start the performance analysis of your web page.

  • Step 3: After the analysis is complete, PageSpeed Insights will provide you with a detailed report of your website’s performance, including suggestions for improvement.

  • Step 4: Look for specific recommendations related to JavaScript. PageSpeed Insights may indicate unused or unnecessary JavaScript files that can be removed or optimized.

  • Step 5: PageSpeed Insights provides a Coverage tab that shows your web page’s JavaScript coverage. This feature helps you understand which parts of your JavaScript code are actually used and which are not.

    • Click on the Coverage tab to view the details.

    • The Used JavaScript section shows the percentage of JavaScript code executed during the page load.

    • The Unused JavaScript section highlights the code that is not used.

  • Step 6: Examine the Unused JavaScript section to identify the specific files or code blocks that are not being utilized. These are good candidates for removal or optimization.

  • Step 7: Depending on the findings, you can take the following actions:

    • If a file is flagged as unused and it is not needed for the functionality of your website, you can safely remove it from your codebase.

    • If only specific portions of a JavaScript file are unused, consider refactoring or optimizing those code blocks to remove unnecessary code.

  • Step 8: After making the changes, run the analysis again with PageSpeed Insights to verify the impact of the changes and to identify any further opportunities for optimization.

In conclusion, PageSpeed Insights helps identify unused JavaScript and performance bottlenecks on your website. So, regular use and recommended actions can help you reduce JavaScript usage and enhance website performance.

Find unused JavaScript by GTmetrix

GTmetrix is a popular web performance testing tool that offers insights into website optimization. In particular, it provides metrics and recommendations to help identify and reduce unused JavaScript on websites.

Find unused JavaScript by GTmetrix

Here’s how you can make use of GTmetrix to reduce unused JavaScript:

  • Step 1: Enter your website’s URL into the GTmetrix testing tool. GTmetrix will analyze your website’s performance and provide a detailed report containing various performance metrics.

  • Step 2: GTmetrix generates a PageSpeed score, which indicates how well your website is optimized for speed. A low PageSpeed score may indicate potential areas for improvement, including reducing unused JavaScript.

  • Step 3: Identify unused JavaScript files in the chart and investigate if they have a long loading time or are not required for the initial page load. GTmetrix creates a waterfall chart to visualize website resource loading.

  • Step 4: Look for large JavaScript files that contribute significantly to the overall page weight because large files are more likely to contain unused code that can be removed or optimized.

  • Step 5: Optimize JavaScript delivery by utilizing code splitting and bundling techniques. These techniques involve splitting your JavaScript code into smaller chunks and only loading the necessary portions when required.

  • Step 6: GTmetrix often suggests optimizing JavaScript, caching, and other techniques for website performance. Following these recommendations can help reduce unused JavaScript and improve overall website performance.

GTmetrix offers valuable insights but doesn’t directly identify unused JavaScript code. So, manual code review and analysis are essential for effective removal. Other tools and techniques can complement GTmetrix and perform a consistent audit of your website’s JavaScript code.

How to reduce unused JavaScript from your website?

1. Identify the unused JavaScript

Identifying and removing unused JavaScript from your website is essential in optimizing its performance and reducing unnecessary load times. By eliminating unused code, you can improve the efficiency of your website and enhance the overall user experience.

Identify the unused JavaScript

Here’s a guide on how to identify and remove unused JavaScript from your website:

  • Review the website’s JavaScript codebase, and identify unused or unnecessary areas.

  • Utilize code editors or an integrated development environment for advanced search capabilities.

  • Optimize website analytics for performance improvement on high-traffic pages.

  • Disable JavaScript sections temporarily without permanently deleting them.

  • Utilize browser tools for analyzing JavaScript usage and reloading webpages.

  • Utilize static analysis tools to detect unused variables, functions, or imports.

  • Utilize tree-shaking in modern JavaScript frameworks to eliminate unused code during the build.

To sum up, maintaining and updating your website’s JavaScript codebase is important for optimal performance and a seamless user experience, but remember to be cautious not to remove code with dependencies or specific scenarios.

2. Review dependencies

To reduce unused JavaScript, reviewing dependencies is also important for optimizing website performance, because web applications accumulate complexity, causing bloated code and reduced performance.

Review dependencies

To address this issue, conducting a thorough review of dependencies is recommended. Here are the steps involved in the process:

  • Identify JavaScript dependencies in your website using package.json.

  • valuate dependencies’ usage and necessity using logs, network traffic, and browser developer tools.

  • Compare dependencies for lightweight alternatives, exploring new libraries or built-in features.

  • Eliminate website dependencies using tools for script tags, module imports, and package uninstallation.

  • Test and validate your website after removing unused dependencies to ensure functionality and avoid side effects.

  • In summary, you should regularly review dependencies and reduce unused JavaScript to improve your website performance, reduce page load times, and enhance user experience, positively impacting SEO.

3. Test and verify

Test and verify

The Test and Verify method involves a systematic process of testing and analyzing your website’s JavaScript usage to identify and eliminate unused scripts. Let’s delve into the steps involved in this approach:

  • Create a comprehensive inventory of JavaScript files on your website.

  • Create a test environment to safely remove JavaScript without affecting the live website.

  • Analyze website traffic and user interactions, and optimize critical pages first.

  • Utilize browser developer tools for optimizing web pages, and analyzing network requests, and JavaScript files.

  • Remove redundant scripts from your website, create backups, and avoid unintended consequences.

  • Test your website functionality and verify JavaScript-dependent elements after removing unused scripts.

By testing and verifying, you can identify and remove unused JavaScript from your website, improving performance, loading times, and user experience. Remember to prioritize user-centric optimization and thoroughly test changes before implementing them on live websites.

4. Remove or optimize the unused JavaScript

Optimizing unused JavaScript is needed for website performance and efficiency, as excessive accumulation can slow loading times and consume resources, negatively impacting user experience.

Remove or optimize the unused JavaScript]()
Here are some effective approaches to remo

Here are some effective approaches to remove or optimize unused JavaScript from your website:

  • Conduct a thorough code review to remove unnecessary JavaScript segments.

  • Understand JavaScript dependencies, identify unnecessary scripts, and remove them.

  • Use code coverage tools to analyze JavaScript execution, identify unused code blocks, and remove them safely.

  • Bundle and minify JavaScript for faster loading times.

  • Improve website performance by loading scripts asynchronously.

  • Delay the loading of JavaScript files until they are needed through lazy loading.

  • Use the content delivery network to deliver JavaScript files, improving page load times.

  • Regularly update website JavaScript usage, remove unused code, and optimize performance.

By implementing these strategies, you can optimize website performance by removing unused JavaScript can enhance user experiences, engagement, and search engine rankings. Also, you should test your website after changes to ensure functionality works as expected.

5. Update references and dependencies

One of the most essential steps when optimizing your website’s performance is to reduce unused JavaScript, and updating references and dependencies is an effective method. Doing so can eliminate unnecessary code and ensure that your website loads faster, improving the overall user experience.

Update references and dependencies

Here are some recommendations:

  • Review your website codebase for unnecessary JavaScript files, scripts, and unutilized dependencies.

  • Update unused JavaScript files in HTML.

  • Review and remove unused or outdated dependencies from websites’ projects to ensure functionality.

  • Update package managers by analyzing dependencies, removing unnecessary ones, and ensuring necessary packages are included.

  • Optimize build scripts using tools to reduce code bundling and size.

Therefore, updating references and dependencies can help you remove unused JavaScript, improve codebase and loading times, enhance user experience, and boost SEO rankings for websites.

6. Test and monitor

Generally, testing and monitoring can help you identify and remove unused JavaScript from your website, enhancing interactivity and functionality while reducing bloated code and negatively impacting performance.

Test and monitor

To begin the process of identifying unused JavaScript, you can follow these steps:

  • Conduct a thorough code review of your website’s JavaScript files.

  • Analyze website behavior using web analytics tools to identify patterns, and optimize script usage.

  • Use JavaScript profiling tools to measure execution time, performance, resource usage, and code blocks.

  • Compare website performance with and without JavaScript files by A/B testing, assessing user experience and conversion rates.

  • Encourage user feedback, report issues, optimize code, and eliminate unused JavaScript. As a result, it is shown clearly that testing and monitoring are essential steps that can help you identify and reduce unused JavaScript from your website.

Read more: Everything to Know about Magento Support and Maintenance Services

Final thoughts

So there you have it, folks!

We’ve come to the end of our journey to understanding how to reduce unused JavaScript. We started by recognizing the impact of unused JavaScript on our web pages’ performance. Then, we delved into some practical strategies that helped us trim the fat and optimize our codebase.

By following the tips we’ve discussed, you can significantly reduce unused JavaScript shipped to the user’s browser. This translates into faster load times, smoother interactions, and happier visitors.

Remember, though, that reducing unused JavaScript is an ongoing process. As our projects evolve and new features are added, it’s necessary to regularly revisit and reassess our code to identify and eliminate any unnecessary bloat.

So let’s roll up our sleeves, dive into our code, and make the web a better place—one optimized line of JavaScript at a time.

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Vinh Jacker
Hello, I'm the Chief Technology Officer of Mageplaza, and I am thrilled to share my story with you. My deep love and passion for technology have fueled my journey as a professional coder and an ultra-marathon runner. Over the past decade, I have accumulated extensive experience and honed my expertise in PHP development.
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