ArticleZip > Changedetectionstrategy Onpush And Observable Subscribe In Angular 2

Changedetectionstrategy Onpush And Observable Subscribe In Angular 2

Have you ever found yourself struggling with efficiently managing data changes in your Angular 2 application? If so, you're in luck because today, we're diving into the world of change detection strategy, specifically focusing on `OnPush` and `Observable.subscribe` in Angular 2. By understanding how these powerful features work together, you can optimize your app's performance and streamline data handling.

Let's start with a brief overview of change detection strategy. In Angular 2, change detection is the process of detecting data changes and updating the user interface accordingly. By default, Angular uses the `ChangeDetectionStrategy.Default` strategy, where it checks all components for changes on every tick of the JavaScript event loop. This can be resource-intensive, especially in large applications with complex data structures.

This is where the `OnPush` change detection strategy comes into play. When you set a component's change detection strategy to `OnPush`, Angular only performs change detection on the component and its children when one of the following occurs:

- The component's input properties change.
- An event handler is triggered within the component.
- The component triggers change detection explicitly.

By utilizing `OnPush`, you can significantly improve the performance of your Angular 2 application by reducing the number of components that Angular needs to check for changes on each tick.

Now, let's take a look at how `Observable.subscribe` fits into the picture. Observables are a crucial concept in Angular for handling asynchronous data streams. When you subscribe to an Observable, you essentially listen for data emissions and define how to handle those emissions when they occur.

Combining `Observable.subscribe` with the `OnPush` change detection strategy is a powerful technique for optimizing data management in your Angular 2 application. By subscribing to an Observable within a component with `OnPush` strategy, you ensure that the component only updates when new data is emitted by the Observable.

Here's a quick example to illustrate how you can leverage `OnPush` and `Observable.subscribe` in Angular 2:

Typescript

import { Component, OnInit, ChangeDetectionStrategy } from '@angular/core';
import { DataService } from './data.service';

@Component({
  selector: 'app-my-component',
  templateUrl: './my-component.component.html',
  changeDetection: ChangeDetectionStrategy.OnPush
})
export class MyComponent implements OnInit {
  data: any;

  constructor(private dataService: DataService) {}

  ngOnInit() {
    this.dataService.getData().subscribe((newData) => {
      this.data = newData;
    });
  }
}

In this example, we have a component that subscribes to a data service to fetch and update data asynchronously. The component is set to use the `OnPush` change detection strategy, ensuring that it only updates when new data is received from the subscription.

By mastering the `OnPush` change detection strategy and `Observable.subscribe` in Angular 2, you can create more efficient and responsive applications that deliver a superior user experience. Experiment with these techniques in your projects and watch your Angular skills soar to new heights!

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