What is the app.components.ts file in an Angular application?

Overview

Angular is an open-source platform and a JavaScript framework written in TypeScript for building single-page applications. Angular building blocks are components.

The file structure that is created by default in the Angular application components consists of the following files:

  • app.components.css
  • app.components.html
  • app.componen.spec.ts
  • app.component.ts
  • app.module.ts

We’ll discuss the app.component.ts file in this shot.

Code

import { Component } from '@angular/core';
@Component({
  selector: 'app-root',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.scss']
})
export class AppComponent {
  title = 'angular';
}

Code explanation

  • Line 1: The import of the Component class that is defined in the module @angular/core is being done in this line.

  • Lines 3-7: The reference to the selector, templateUrl, and styleUrls are given in the declarator. The selector is a tag that is used to be placed in the index.html file.

The Component decorator allows the user to tag a class as an Angular component. Additional information in the metadata determines how the component should be instantiated, processed, and used at the runtime.

  • selector identifies the directive in the template and triggers the instantiation of the respective directive.

  • templateUrl is the relative or the absolute path of the template file for an Angular component.

  • styleUrls are the relative or absolute paths containing CSS stylesheets for the component. There can be one or more URLs in the component decorator.

  • Lines 8-10: The AppComponent class has a title variable, which is used to display the application’s title in the browser. In this case, angular will be shown in the browser.

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