Component

@Component

1. style/styleUrl: a CSS stylesheet defines the style of component
2. template/templateUrl: defines theHTML that renders into DOM
3. selector : defines the HTML tag of the component, equivalent to customElements.define(CustomComponent, custom)

use other components to build page

add imports: [comp1, comp2, ....] to import the components we need

import {UserLoginComponent} from "user-login.ts"
@Component({
    selector: 'user-profile',
    templateUrl: 'user-profile.html'
    styleUrl: 'user-profile.css',
    imports: [UserLoginComponent]
})
export class UserProfileComponent() {...}