Angular 2.0: What's New, Release History & Support Lifecycle

What Is New in Angular 2.0

Angular 2.0 is a complete platform rewrite, focusing on performance, mobile support, and modern development practices. It introduces a component-based architecture, a new dependency injection system, and a streamlined change detection mechanism.

How does the component model change application structure?

Angular 2 shifts from the MVC controller pattern to a hierarchical component architecture. Everything is a component, which bundles its template, logic, and styles into a single cohesive unit.

This approach simplifies large-scale application development by enforcing a clear and predictable structure. Components are nestable and communicate through well-defined inputs and outputs, making code more reusable and easier to reason about.

Example Component

import { Component } from '@angular/core';
@Component({
  selector: 'my-app',
  template: `<h1>Hello {{name}}</h1>`
})
export class AppComponent {
  name = 'Angular 2';
}

What is the new template syntax and data binding?

The new syntax removes many directives from AngularJS and replaces them with a simpler, more intuitive system. Property bindings use square brackets [property], event bindings use parentheses (event), and two-way binding uses the banana-in-a-box syntax [(ngModel)].

This change eliminates confusion between HTML attributes and DOM properties. In practice, it means more explicit and predictable data flow in your templates, which drastically reduces bugs related to binding context.

How does dependency injection work now?

Dependency Injection (DI) is now hierarchical and leverages ES2016 decorators. You inject dependencies directly into a component's constructor, making the dependencies explicit and the code easier to test in isolation.

The hierarchical nature means a component has access to services provided by itself and all its ancestors. This is powerful for creating application-wide singletons or scoping services to specific parts of your component tree.

Example Dependency Injection

import { Injectable } from '@angular/core';
@Injectable()
export class HeroService {
  getHeroes() { return HEROES; }
}
@Component({
  // ...
  providers: [HeroService]
})
export class HeroListComponent {
  constructor(private heroService: HeroService) { }
}

What performance improvements were made?

Angular 2 introduced a radical change detection system that is orders of magnitude faster. It uses generated code and zones to automatically know when to check for changes, moving from a slow digest cycle to a targeted, unidirectional flow.

Ahead-of-Time (AOT) compilation is a game-changer. It compiles templates during the build process, resulting in smaller bundle sizes, faster rendering, and earlier template error detection. The framework itself is also built with tree-shaking in mind from the start.