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Angular Web Components: Create Reusable UI with Angular E…

Posted on by William Zheng

Ever wondered how to make your Angular components work seamlessly outside your own project? You’re not alone. As web applications become more interconnected, many developers want reusable building blocks that can live anywhere—on any framework or website.

Understanding how Angular web components work is key to unlocking this flexibility. In this article, you’ll discover what Angular web components are, why they matter, and step-by-step guidance for building and using them effectively. Let’s dive in!

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How Angular Web Components Work

Angular, one of the most popular front-end frameworks, offers a robust way to build dynamic and maintainable applications. But what if you need to use Angular components outside of an Angular application—or want to share your UI components across projects built on different tech stacks? This is where the concept of Angular web components, also called Angular Elements, comes into play.

Angular web components allow you to package your Angular components as standards-based custom elements. These custom elements can then be reused in any web page, regardless of the framework or libraries it uses. Let’s break down what this means, how it works, and why it can be a game-changer for scalable, maintainable web development.

What Are Angular Web Components?

Angular web components utilize the concept of Web Components, a W3C standard for reusable UI building blocks. In Angular, you can transform your components into “custom elements”—native browser elements that work anywhere.

Key Characteristics

  • Framework-Agnostic: Once created, the component doesn’t need Angular to function.
  • Reusable: Drop it into React, Vue, or plain HTML pages.
  • Encapsulated: The component’s styles and functionality stay self-contained.

Why Use Angular Web Components?

With ever-growing project sizes and diverse technology stacks, providing a reusable component library is invaluable. Here are some reasons why Angular web components are becoming a hot solution:

  • Cross-Framework Compatibility: Share Angular components with non-Angular projects.
  • Micro-Frontends: Build independently deployable pieces of a large web app.
  • UI Consistency: Enforce a single design library across multiple apps.
  • Incremental Migration: Gradually migrate or integrate Angular into legacy applications.

How Do You Build Angular Web Components?

The Angular CLI, combined with the Angular Elements package, makes the process remarkably straightforward. Let’s walk step-by-step through converting an Angular component into a web component.

1. Prepare Your Angular Project

First, ensure you’re working with Angular version 6 or above, which has built-in support for Angular Elements.

Tip: Keep your components as standalone as possible. The fewer external dependencies, the better.

2. Add Angular Elements

Add the necessary package:

ng add @angular/elements

This package enables you to transform Angular components into custom elements.

3. Create a Component

You can transform any Angular component, but for best results, create one whose API (inputs/outputs) is self-contained.

// Example: greeting.component.ts
import { Component, Input } from '@angular/core';

@Component({
  selector: 'greeting-element',
  template: `Hello, {{name}}!`
})
export class GreetingComponent {
  @Input() name = 'World';
}

4. Register as a Custom Element

In your application’s entry point (often main.ts or a module bootstrap file), you’ll use Angular’s createCustomElement function.

import { NgModule, Injector } from '@angular/core';
import { createCustomElement } from '@angular/elements';
import { GreetingComponent } from './greeting.component';

@NgModule({
  declarations: [GreetingComponent],
  entryComponents: [GreetingComponent],
})
export class AppModule {
  constructor(private injector: Injector) {}

  ngDoBootstrap() {
    const GreetingElement = createCustomElement(GreetingComponent, { injector: this.injector });
    customElements.define('greeting-element', GreetingElement);
  }
}

Here’s what’s happening:

  • createCustomElement wraps your Angular component as a native browser custom element.
  • customElements.define registers it by its tag name.

5. Build and Use

Build your application:

ng build --prod --output-hashing=none

You’ll typically take the produced JavaScript files and reference them in any HTML page—even outside Angular.

Example Usage:

And that’s it—your Angular component now works as a web component anywhere!

Benefits of Angular Web Components

The approach comes with many practical advantages:

1. Code Reusability

  • Build, package, and distribute once; use everywhere.
  • Simplifies UI library development.

2. Cross-Team Collaboration

  • Teams using different frameworks can share base components.
  • Promotes design system adoption across your organization.

3. Upgrade Friendly

  • Isolate migrations and upgrades to your Angular codebase.
  • Use updated components with old apps through web components.

4. Micro-Frontend Architecture

  • Structure large applications as separate, independently deployable pieces.

5. Encapsulation

  • Scoped styles and logic prevent accidental interference.

Challenges and Caveats

While Angular web components offer many benefits, there are several challenges to consider:

1. Bundle Size

  • Out of the box, Angular brings in a significant runtime.
  • Web components exported from Angular can be larger than native or lightweight framework counterparts.

Tip: Employ optimization steps like tree-shaking and code splitting. Consider using Angular’s standalone components (from Angular 14+) for even leaner bundles.

2. Browser Compatibility

  • Most modern browsers support Web Components natively.
  • For legacy browsers, you may need polyfills.

3. Change Detection

  • Web component inputs update only when their attributes change.
  • Angular’s change detection works differently than React or Vue; careful management of property updates is necessary.

4. Dependency Management

  • Avoid including duplicate dependencies when using multiple Angular web components on a page.

5. Inter-Component Communication

  • Custom event emission works, but managing complex communication (like with services or shared stores) can become tricky.

Best Practices for Angular Web Components

Here are some practical tips to help you create robust, high-performing Angular web components:

Keep It Small and Focused

  • Design each component around a single responsibility.
  • Avoid unnecessary dependencies.

Use Standalone Components

  • Angular’s standalone components (introduced in v14) work well for web components, reducing bundle size.

Optimize Output

  • Enable build optimizations (--prod), lazy loading, and output hashing where possible.
  • Consider removing the Angular dev tools and zone.js when not needed.

Scope Styles Carefully

  • Use Angular’s encapsulated styles, but be mindful of global style bleed.
  • Test your component in various host applications to ensure style integrity.

Version and Document Your Components

  • Treat your components as mini-libraries:
  • Employ semantic versioning.
  • Write clear documentation.
  • Provide API usage examples.

Cost Tips (Shipping Considerations)

While using Angular web components doesn’t directly involve shipping goods, there are some “shipping” tips in the software sense:

  • Bundle Size Matters: Smaller bundles mean faster loading times, saving you on cloud hosting and CDN costs.
  • Cache Your Bundles: Leverage browser caching to minimize repeated “shipping” (downloading) to users.
  • Lazy Load: Only send (“ship”) code to browsers when needed, reducing data transfer.
  • Tree Shaking: Remove unused code before shipping your bundle for better performance and lower costs.

Real-World Use Cases

Many organizations are leveraging Angular Elements (web components) for:

  • Embedding reusable UI elements (like buttons, date pickers, dialogs) in multiple web apps.
  • Gradually migrating legacy JSP, AngularJS, or other frontend applications by injecting Angular-based components one at a time.
  • Distributing in-house design system components through private npm packages as web components.

Conclusion

Angular web components—or Angular Elements—offer a powerful way to create self-contained, reusable UI building blocks. By exporting your Angular components as standard web components, you dramatically expand the reach and value of your code. Whether you want to support cross-framework projects, establish a solid design system, or build scalable micro-frontends, this technique is worth learning and applying.

A thoughtful approach to bundling, documentation, and communication patterns will ensure your Angular web components are robust, efficient, and easy to use—no matter where they’re deployed.

Frequently Asked Questions (FAQs)

What is an Angular web component?

An Angular web component is essentially an Angular component packaged as a browser-native custom element. It can be used in any web page or application, regardless of the framework used to build it.

How do I use an Angular web component in a non-Angular application?

Build your Angular web component, include the generated JavaScript files in your HTML, and use the custom HTML tag defined by your component. No Angular setup is required in the host application.

Can I use Angular web components in other frameworks like React or Vue?

Yes! That’s the main advantage. Once exported as web components, they can be used just like any standard HTML element—inside React, Vue, or even jQuery projects.

Are there any performance concerns with Angular web components?

Bundle size is the main concern. Angular’s runtime can make your component files larger compared to minimalistic solutions. Optimize by keeping components lean and enabling build optimizations.

Do Angular web components work in all browsers?

Most modern browsers support web components. However, if you need to support older browsers (like Internet Explorer 11), you’ll need to include polyfills for web component standards.

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