Brandon Almeda - Author
Brandon Almeda
  • Sep 5, 2023
  • 2 min read

Improve Fast Site Performance with Tree Shaking in Web Design & Development

Team building at RGB Parkour Tour back in 2014.

This is now available for purchase on print and a variety of other merch over in my RedBubble store. If you like the image, please consider making a purchase to help support me! :) - Tree shaking

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Introduction to Tree Shaking

In the dynamic world of web development, performance is pivotal. For JavaScript projects, bundlers like Webpack and Rollup are widely used tools that aggregate numerous individual JS code files into a single 'bundle.js'. However, this monolithic JavaScript file can become excessively large, leading to slower website loading times, and consequently, a less optimal user experience. Alleviating this issue, there is a powerful and increasingly popular strategy known as 'tree shaking.'

Tree shaking, or dead code elimination, is a method used primarily in JavaScript web development to expel unused or 'dead' code from a final file bundle. Originally coined by the ES2015 module syntax, the term 'tree shaking' metaphorically suggests the act of a tree being shaken to eliminate dead leaves, similarly leaving our codebase with only the living, practical, and necessary parts.

Not only does tree shaking enhance application performance, but it also considerably improves code efficiency. By eliminating superfluous code, it reduces the size of the final bundle, leading to faster load times, improved performance, and an overall better user experience.

Moreover, tree shaking is conducive to cleaner, more maintainable code by assisting developers in spotting unused dependencies or modules that have been involuntarily incorporated. Therefore, learning about tree shaking is essential, particularly for developers aiming to build efficient, high-performing web applications.

As we proceed with this article, we will delve deeper into the concept, implications, and the methodology of successfully implementing tree shaking in JavaScript projects. We'll explore its benefits, how it operates within various bundlers, and provide real examples to further elucidate its significance. Whether you're an experienced developer or new to JavaScript, understanding and applying 'tree shaking' can substantially enhance your code's performance and efficiency.

Understanding the Basics of Tree Shaking

Tree shaking, an influential concept in modern web development, is an essential technique for optimizing performance and reducing the size of your JavaScript bundles. This term refers to the removal of unused or "dead" code from the final output file to considerably lighten the load, enhancing site speed and overall user experience. In this piece, you'll step into the basics of tree shaking and how it plays a significant role in the efficient packaging of modern JavaScript applications.

The term "tree shaking" is derived from the image of shaking a tree to make the dead leaves fall. In the context of coding, the "dead leaves" are the unused codes or modules in an application. By applying tree shaking, we optimize our code by "shaking out" the unused modules, hence the name.

Tree shaking works on the principle of static imports, which are part of ES2015 module syntax. Using import and export statements, programmers reveal which parts of their code are dependencies for other code sections. The process uses these markers to extract and bundle only those portions of the code that are needed, avoiding the importation of unused or unnecessary code parts.

Tree shaking has become particularly useful with the introduction of single-page applications (SPAs) where JavaScript bundles could grow fairly large. As an optimized technique, it plays a vital role in preventing bloat and maintaining operational efficiency.

Leveraging this technology with tools like Webpack, Rollup.js, or Parcel provides a more efficient build process. Just ensure your application is using ES2015 module syntax (import and export), and opt-in to the process in your bundler’s configuration to start benefiting from tree shaking.

Lastly, remember that tree shaking might not work efficiently if you use a package with side effects that run when the package is imported. It is better to avoid including such packages in your project, or to mitigate side effects where possible.

By understanding this innovative process, you can efficiently assist in maintaining the performance of your application and the usability of your JavaScript projects. Now, that's truly worth shaking a tree for.

How Tree Shaking Complements Code Splitting

Tree Shaking and Code Splitting are two powerful concepts that, when combined together, can significantly streamline the coding efficiency and final output.

Fundamentally, Tree Shaking is a technique that eliminates unnecessary or dead code paths from your final production bundle. By keeping only required modules, it scales down the application size, thus reducing the loading time and improving performance. Tools like webpack and Rollup.js powerfully facilitate this technique by employing static analysis to map out the unused code segments.

On the other hand, Code Splitting is a simple but effective method to separate your codebase into smaller chunks. Larger, monolithic codebase often becomes difficult to maintain, inefficient and tends to weigh down the performance. Code Splitting allows you to divide your code into smaller bundles that can be lazy loaded, significantly boosting loading speed and improving user experience, by only delivering what the user needs when they need it.

The potency of Tree Shaking and Code Splitting is amplified when used together. Employed independently, they serve their purpose, but when combined, they provide an exceptionally potent method to keep your codebase lean and efficient.

With Tree Shaking, unnecessary codes are pruned out. The disconnecting and removal of dead code paths can drastically reduce the size of your final bundle. Afterwards, applying Code Splitting to the ‘shaken’ codebase makes it even more efficient by converting it into manageable chunks that are loaded only as per requirement.

You can say that Tree Shaking and Code Splitting complement each other, shaping an application that is not only efficient and maintainable but also served optimally to the user. Further integrating these two concepts into your development process can result in significantly improved performance, faster loading times, and improved SEO rankings due to better user experience.

This section indeed affirms that together, Tree Shaking and Code Splitting hold the recipe to a better, more efficient, and performance-optimized web application.

Implementation of Tree Shaking in Web Design & Development

In a rapidly digitizing world, web development has sought advanced optimization practices to enhance user experience. Amongst these techniques, 'Tree Shaking' has garnered recognition, significantly trimming the load time by eliminating redundant or unused code.

In simpler words, Tree Shaking is akin to shaking a tree to drop out dead leaves — useful code stays, while redundant code falls away — enhancing your web performance.

Tree Shaking is derivative of ECMAScript 2015 Module (ES6) system where static import/export statements allow the parser to identify extraneous code paths. This static structure presents a clear insight into which modules, variables, or functions are used, and which aren't.

Modern-day web development chiefly deploys Javascript modulating bundlers such as Webpack or Rollupjs for Tree Shaking. Although browsers do not support ES6 directly; Webpack and Rollupjs, while combining files using AST (Abstract Syntax Tree), identifies, and eradicates dead code: a technique known as Dead Code Elimination (DCE).

Implementing Tree Shaking involves a sequence of steps. Firstly, start by utilizing ES6 modules rather than CommonJS. This enables Tree Shaking capabilities, as ES6 allows static analysis of your code. Secondly, configure your Babel transpiler to avoid transpiling these modules. To do this, set the "modules" in your .babelrc file to false. Finally, Webpack can identify the dead code but does not remove it. Thus, including a minifier like UglifyJSPlugin in your webpack.config.js helps in removing the dead code during output.

Remember, for fruitful Tree Shaking, your dependencies too should be composed of ES6 modules. Often package.json files have a module field specifying the location of the ES6 module.

The implementation of Tree Shaking is a judicious approach, potentially improving web design and development. A faster page load uplifts user experience, escalates SEO rankings, reduces bounce rates, and increases conversion rates, leading to a streamlined and efficient website. Although it may seem complex initially, the substantial benefits it offers are undeniable.

Examples of Improved Site Performance through Tree Shaking

Tree shaking, an optimization technique applicable to Javascript, is a fundamental practice for many high-performance websites. By eliminating unused code from the final bundles, tree shaking significantly reduces the overall size of a website or application, thereby enhancing the site’s performance. Here are few examples highlighting the potential improvements afforded by tree shaking.

Case Study 1: Removing Unused Utility Functions

A real-world application of tree shaking is the removal of excessive utility functions found in libraries like lodash or underscore. These libraries provide a variety of functions, many of which often remain unutilized. Tree shaking can identify and discard such redundant functions thus reducing the JavaScript bundle size. This facilitates quicker downloads and faster parsing by the browser, ultimately leading to quicker rendering of the web page.

Case Study 2: Modular Javascript Code

JavaScript code is typically bundled into small modules with dedicated functionalities to improve maintainability. However, not all code written is utilized, leading to bloated and sluggish applications. Tree shaking, integrated with tools like Webpack or Rollup, facilitates the deterministic and static nature of JavaScript imports, discarding unutilized code and enhancing site performance.

Case Study 3: Removing Unused CSS

Unused CSS rules can inflate style sheets, causing unnecessary data downloads and slower rendering. Various plugins, like PurifyCSS or UnCSS, enable users to remove unutilized CSS at the tree-shaking phase, boosting page load speeds significantly.

Case Study 4: Vue.js

Vue.js, an acclaimed JavaScript framework, has led by example in adopting the tree shaking technique. Their design allows for the exclusion of unused parts of the Vue library in the final build, maximizing load speed and enhancing website performance.

These examples demonstrate tree shaking’s potential impact in reducing delivery times and improving website performance. It provides a valuable mechanism for the elimination of unutilized code, ensuring your site stays lean and efficient, whether you're dealing with JavaScript or CSS. Optimal site performance is crucial in retaining users and tree shaking can facilitate this by providing a smooth and responsive browsing experience.


To sum up, tree shaking is a fundamental principle which plays a pivotal role in optimizing JavaScript applications. It assists in eradicating any dead or unused code, streamlining the app performance, and making the overall user experience more fluid and instantaneous. By adopting tree shaking techniques, developers can tap into increased efficiency, leading to a well-optimized codebase and friendlier storage requirements.

Incorporating tree shaking increasingly becomes a necessity as your application grows and becomes more complex, and managing unused code begins to become onerous.

When dealing with ES6 modules, tree shaking operates natively, effectively removing unused exports. Albeit, it is worth noting that you have to be mindful of your code structure and usage to ensure the optimal utilization of tree shaking.

Furthermore, tools such as Webpack and Rollup.js provide an out-of-the-box tree shaking feature. Even so, it is essential to know that tree shaking only works when there's an import and export syntax. Thus, using the import statement for side effects may prevent the tree shaking technique from operating effectively.

Grasping the nuances and quality of the code, developers can make their applications more maintainable and optimized, immersing them in testing tree shaking on existing projects.

The strength of tree shaking as a front-end development strategy cannot be understated. If you are a developer and haven't yet explored this potent tool, it is high time to delve into it and understand how it can invigorate your application's performance. With more extensive library functionalities available now, developers have the perfect opportunity to implement tree shaking and propel their coding skills to new heights.

In our hyper-digital world, where speed and efficiency are of essence, mastering tools like tree shaking is no longer optional - it's a necessity. So, equip yourself with knowledge, shake off the dead code, and let your applications thrive.

Web Design & DevelopmentFast Site PerformanceCode splittingTree shaking