Tree Shaking

21 Jun 20256 minutes to read

Tree shaking is a powerful optimization technique in modern JavaScript and TypeScript development that eliminates unused or “dead” code from your application’s final bundle. This results in smaller, more efficient, and faster-loading web applications. The term “tree shaking” comes from the idea of shaking a tree to remove dead leaves, leaving only what’s essential.

Tree shaking relies on the static structure of ES2015 (ES6) module syntax—specifically import and export statements. Tools like Webpack and Rollup analyze these modules during the build process, identifying and removing code that isn’t imported or used in your application. For example, if you export a function in a module but never import it elsewhere, tree shaking ensures it won’t bloat your bundle. This optimization is especially valuable for large applications or when using feature-rich libraries like Syncfusion’s Angular components.

In this guide, we’ll explore how tree shaking works in Angular, how it integrates with Syncfusion^® Angular components, and how you can implement it to boost your application’s performance.

Tree Shaking in Angular

Angular has supported tree shaking since Angular CLI version 2, thanks to its use of Webpack as the underlying bundler (and later, options for other tools like esbuild). Tree shaking in Angular leverages ES2015 module syntax to ensure that only the code you actually use makes it into your production bundle.

The process is tightly integrated with Angular’s Ahead-of-Time (AOT) compilation, which became the default starting with Angular version 9. AOT compilation pre-compiles your Angular templates and components into efficient JavaScript during the build process, rather than at runtime. This pre-compilation allows the Angular compiler to analyze your code more effectively, marking unused portions for removal during tree shaking. The result? Faster load times, reduced bundle sizes, and an improved user experience.

For example, if you import a component but don’t use it in your templates or logic, AOT and tree shaking work together to exclude it from the final output. To learn more about AOT compilation, check out the AOT documentation.

Using Syncfusion^® components with Tree Shaking

Syncfusion^® Angular components, part of the Essential JS 2 (EJ2) library, are designed with tree shaking in mind. They are structured as modular, tree-shakable packages by default, meaning you don’t need to make special adjustments at the application level to benefit from this optimization.

Each Syncfusion^® component is split into individual modules, allowing you to import only what you need. For instance, when using the Syncfusion^® DataGrid, you can import the GridModule for basic functionality or add specific feature modules like PageService or FilterService as required. This modularity ensures that unused features are excluded from your bundle during tree shaking, keeping your application lean.

To take full advantage of this, use precise imports in your code. For example:

import { GridModule } from '@syncfusion/ej2-angular-grids';
import { PageService } from '@syncfusion/ej2-angular-grids';

Avoid importing the entire library (e.g., GridAllModule) unless you need all features, as this will include everything and negate the benefits of tree shaking.

Implementing Tree Shaking in an Angular Application

Here’s a step-by-step guide to implementing tree shaking in an Angular application with Syncfusion^® components:

1. Create an Angular Application
   Start by setting up a new Angular project and adding the Syncfusion^® DataGrid component. Follow the Getting Started guide for Angular Standalone projects to get up and running.

2. Configure for Tree Shaking
   Modify your angular.json file to enable production optimizations, including tree shaking. Update the "production" configuration as follows:

   "configurations": {
       "production": {
           "optimization": true,          // Enables minification and tree shaking
           "outputHashing": "all",        // Ensures unique file names for caching
           "sourceMap": false,            // Disables source maps for smaller builds
           "namedChunks": false,          // Reduces bundle size by avoiding named chunks
           "aot": true,                   // Enables AOT compilation
           "extractLicenses": true        // Separates licenses for compliance
       }
   }

   • optimization: true: Activates Webpack’s optimization features, including tree shaking and minification.
   • aot: true: Ensures AOT compilation, which enhances tree shaking by pre-compiling your code.
3. Build the Application
   Run the following command to build your app with tree shaking enabled:

   ng build --configuration=production
   

   Alternatively, use ng serve --configuration=production for local testing (though this is less common for production builds).

4. Verify the Bundle Size
   After building, analyze your bundle with the source-map-explorer tool:

   npm install -g source-map-explorer
   source-map-explorer dist/your-app/*.js
   

   This tool visualizes what’s in your bundle, helping you confirm that unused code has been removed.

For a working example, explore the Angular Tree Shaking Example on .

By following these steps, you’ll optimize your Angular application’s performance and deliver a faster experience to users.

Bundle size for Syncfusion^® Angular Grid component

The table below shows the bundle sizes for an Angular application using the Syncfusion^® DataGrid component after tree shaking has been applied. These sizes reflect a production build with the configurations outlined above.

• Raw Size: The uncompressed size of the bundle.
• Transfer Size: The compressed (gzipped) size, which is what users download.

These numbers demonstrate how tree shaking keeps bundle sizes manageable by including only the features you import. For comparison, using GridAllModule instead of GridModule would significantly increase the size (e.g., over 2 MB raw), as it includes all DataGrid features regardless of usage. Stick to GridModule and add feature modules (like PageService) only as needed. Learn more about DataGrid feature modules in the official documentation.