How to use web components in Angular applications

Angular is a popular framework for building modern web applications. It provides a number of features and tools that make it easy to create complex applications. In this post, we will explore how to use web components in Angular with examples.

Web components are a set of web platform APIs that allow developers to create custom HTML elements with their own functionality and styles. They are a powerful tool for building reusable and modular components that can be used across different projects.

To use web components in Angular, we need to create a custom element and register it with the browser. Angular provides a number of tools and APIs that make it easy to create custom elements and register them with the browser.

Step 1: Create a new Angular component

First, we need to create a new Angular component that will act as our custom element. We can use the Angular CLI to generate a new component:

ng generate component my-custom-element

This will create a new component in the src/app folder.

Step 2: Implement the custom element interface

Next, we need to implement the custom element interface in our component. The custom element interface defines the methods and properties that our component needs to implement in order to be a valid custom element.

We can implement the custom element interface by adding the following code to our component class:

import { Component, OnInit, OnDestroy, Input } from '@angular/core';

@Component({
  selector: 'my-custom-element',
  templateUrl: './my-custom-element.component.html',
  styleUrls: ['./my-custom-element.component.css']
})
export class MyCustomElementComponent implements OnInit, OnDestroy, CustomElement {

  @Input() text: string;

  constructor(private host: ElementRef) {}

  connectedCallback() {
    console.log('Custom element connected to the DOM');
  }

  disconnectedCallback() {
    console.log('Custom element disconnected from the DOM');
  }

  attributeChangedCallback(name: string, oldValue: any, newValue: any) {
    console.log(`Attribute ${name} changed from ${oldValue} to ${newValue}`);
  }

  ngOnInit() {
    console.log('Custom element initialized');
  }

  ngOnDestroy() {
    console.log('Custom element destroyed');
  }

}

In this example, we have implemented the custom element interface by defining the connectedCallback, disconnectedCallback, and attributeChangedCallback methods. We have also implemented the OnInit and OnDestroy Angular lifecycle hooks.

Step 3: Register the custom element with the browser

Once we have implemented the custom element interface, we need to register the custom element with the browser. We can do this by using the createCustomElement function provided by the @angular/elements package.

We can register the custom element by adding the following code to our app.module.ts file:

import { NgModule, Injector } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { createCustomElement } from '@angular/elements';
import { MyCustomElementComponent } from './my-custom-element/my-custom-element.component';

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

  ngDoBootstrap() {
    const customElement = createCustomElement(MyCustomElementComponent, { injector: this.injector });
    customElements.define('my-custom-element', customElement);
  }
}

In this example, we have imported the createCustomElement function from the @angular/elements package. We have also added the MyCustomElementComponent to the declarations and entryComponents arrays in our module.

In the AppModule class, we have implemented the ngDoBootstrap method and used the createCustomElement function to create a new custom element based on our MyCustomElementComponent. We have also used the customElements.define method to register the custom element with the browser.

Step 4: Use the custom element in our application

Now that we have created and registered our custom element, we can use it in our application just like any other HTML element.

In our example, we can use the my-custom-element tag in any HTML template and pass in the text input property like this:

<my-custom-element [text]="'Hello world'"></my-custom-element>

When the custom element is rendered, the text the property will be passed to the component and displayed in the template.

Conclusion

Using web components in Angular allows us to create reusable and modular components that can be easily shared across different projects. With the help of the @angular/elements package, we can create and register custom elements with the browser and use them in our application just like any other HTML element.

By following the steps outlined in this post, you should be able to start using web components in your Angular applications and take advantage of their many benefits.

Web Component advantages in detail: https://vibhas1892.medium.com/web-components-and-its-usges-99214db79d82

Thanks for Reading!!!!