Communication between components

https://angularfirebase.com/lessons/sharing-data-between-angular-components-four-methods/angularfirebase.com

@input @output

Subject observable in a service

@Host() && @Contentchildren()

To be used when components child and parent work intricately together like an item component and a list item... and you want to make accessible from the exterior only the parent component for example

@Host allow to have access to the parent component within the child component. Instead of passing the data from parent to child thanks to @Input. It could be more convenient to use @Host().

The advantages are :

• nothing to set in the templates... all is available

@ContentChildren is the contrary being able to access the child property from a parent component

Angular + Redux

Use services

Services are in angular a way to extract logic from the components to be used everywhere. Services are mostly used to get data from the API and as utility services to package data handling logic...or to provide utility like logging, web socket...

Component that extend a parent component

export class WidgetMessageComponent  extends WidgetComponent implements OnInit

This syntax uses prototypal inheritance to make WidgetMessageComponent a sub class of WidgetComponent

Practically :

• the @component decorator is not overridable

• any properties, functions defined in inherited component is also available in the component that inherited it

• when user constructor definition in child component (the component that extend)

constructor(
    private route: ActivatedRoute,
  ) {
    super();
  }