Expert Angular

TypeScript Observable

Let's take a look at the following Observer/Subject implementation in pure TypeScript (that is no Angular or framework of any kind, just TypeScript).

First, I defined an Observer interface that any concrete implementation will have to implement:

export interface Observer{ 
  
   notify(); 
} 

This interface only defines the notify() method. This method will be called by the subject (that is the Object being observed by Observer) when its state changes.

Then, I have an implementation of this interface, named HumanObserver:

export class HumanObserver implements Observer{ 
  
   constructor(private name:string){} 
  
   notify(){ 
  
               console.log(this.name, 'Notified'); 
   } 
} 

This implementation leverages the typescript property constructor, where ...