The component – a controller and a building block

In the context of MVC, the component is the V and C, the view and the controller. The component allows you to define either a separate template file or an inline template. The template is the view part.

The controller in this context is a component class file that handles user interactions and also fetches the necessary data for the template to display.

Components have come to be a central concept for a lot of frameworks that are popular today, such as React, Vue.js, and Polymer. A component can take inputs, which are either data or methods. It consists of a piece of code and an HTML template, which render interesting data, living on the component. A component in Angular consists of three major parts:

• A decorator function
• A class
• A template

A component consists of a controller class and a template. It can play two different roles in an Angular application: either it can be the responder to the route or it can serve as a building block. In the first case, Angular will instantiate it when a new route happens and respond with that component. In the latter case, the component is created directly by existing as a child component within another component.

We will explain next what we meant by the previous paragraph.