Use the async pipe to handle asynchronous data. In Angular, it is common to work with asynchronous data, such as data retrieved from an API or a database. The async pipe is a built-in Angular pipe that makes it easy to work with asynchronous data in templates. It automatically subscribes to an Observable or Promise and returns the latest value emitted by the Observable or the resolved value of the Promise.

Using the async pipe has several benefits. First, it simplifies the code by removing the need to manually subscribe to an Observable or a Promise. This reduces the amount of boilerplate code and makes the code easier to read and maintain. Second, it ensures that the subscription is properly handled and cleaned up when the component is destroyed. This prevents memory leaks and improves the performance of the application. Finally, it makes the code more reactive and responsive, as the template is automatically updated when the data changes.

import { Component } from '@angular/core';
import { Observable } from 'rxjs';
import { DataService } from './data.service';

@Component({
  selector: 'app-root',
  template: `
    <div *ngIf="(data$ | async) as data">
      <h1>{{ data.title }}</h1>
      <p>{{ data.description }}</p>
    </div>
  `
})
export class AppComponent {
  data$: Observable<any>;

  constructor(private dataService: DataService) {
    this.data$ = this.dataService.getData();
  }
}

In the above example, the async pipe is used to handle the asynchronous data returned by the getData() method of the DataService. The data$ property is an Observable that emits the data when it is available. The async pipe is used in the template to subscribe to the Observable and display the data when it is available. The *ngIf directive is used to ensure that the template is only displayed when the data is available. This ensures that the template does not display any undefined or null values.