Minimum definition of a component Angular 4

Question

What is the minimum definition of a component, After looking at https://angular.io/api/core/Component it seems all are optional. Can some one explain what is the minimum definition.

Answer 1

The absolute minimal configuration for a @Component in angular is a template. Both template properties are set to optional because you have to define either template or templateUrl.

When you don't define them, you will get an exception like this;

No template specified for component 'ComponentName'

A selector property is not required, as you can also use your components in a route.

Answer 2

Minimum configuration for Component is a template,

1. constructor is not required, it is auto generated
2. selector is also optional , component can be accessed via router by class name

3. template is required (either template or templateUrl)

   import { Component } from '@angular/core';
   @Component({
     templateUrl: './minimum.component.html' // or
     template: '' 
   })
   export class MinimumComponent {}