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Angular 2 0 Equivalent To Scope Apply

If you've been working with Angular for a while, you may be familiar with the `scope.$apply()` function in AngularJS, a way to update the data model and trigger a view refresh manually. However, things have changed with Angular 2.0 and above. In this article, we will explore the equivalent of `scope.$apply()` in Angular 2.0 and how you can achieve similar functionality in the latest versions of Angular.

In Angular 2.0 and later versions, there is no direct equivalent to `$apply()` since Angular has evolved its architecture to a component-based system and uses a unidirectional data flow. Instead of manipulating scopes, Angular encourages developers to use the concept of Zones to manage asynchronous operations and change detection.

Zones are execution contexts that allow you to intercept and monitor asynchronous tasks in Angular applications. When a task is executed within a zone, Angular can track its execution and trigger change detection automatically when necessary. This eliminates the need for manual intervention like calling `$apply()`.

To simulate `scope.$apply()` behavior in Angular 2.0, you can leverage Zones to run a function in the Angular zone where change detection is enabled. Here's how you can achieve this:

Typescript

import { NgZone } from '@angular/core';

// Inject NgZone in your component
constructor(private zone: NgZone) {}

// Define a function that needs change detection
updateData() {
  this.zone.run(() => {
    // Code that updates your data model
  });
}

By wrapping your data update logic inside `this.zone.run()`, you ensure that Angular detects the changes and updates the view accordingly within the Angular zone.

Another way to trigger change detection in Angular is by using the `ChangeDetectorRef` service. The `ChangeDetectorRef` provides methods like `markForCheck()` and `detectChanges()` that allow you to inform Angular about changes in your component.

Typescript

import { ChangeDetectorRef } from '@angular/core';

// Inject ChangeDetectorRef in your component
constructor(private cdr: ChangeDetectorRef) {}

// Call markForCheck() or detectChanges() where updates occur
updateData() {
  // Code that updates your data model
  this.cdr.markForCheck();
}

By calling `markForCheck()` or `detectChanges()` after updating the data model, you can manually trigger change detection and update the view.

In conclusion, while Angular 2.0 does not have a direct equivalent to `scope.$apply()` from AngularJS, you can achieve similar results by utilizing Angular's Zones and ChangeDetectorRef. These mechanisms enable you to handle change detection and update views efficiently in the latest versions of Angular.

Keep exploring Angular's evolving ecosystem and leverage modern techniques to build robust and responsive web applications with ease. Happy coding!

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