Another way we can approach this is by taking advantage of the DI pattern. We're already familiar with it from AngularJS; let's demonstrate how we can refactor the preceding code using DI in the context of Angular:

class Engine {...} 
class Transmission {...} 
 
@Injectable() 
class Car { 
  engine; 
  transmission;
 
  constructor(engine: Engine, transmission: Transmission) { 
    this.engine = engine; 
    this.transmission = transmission; 
  } 
} 

All we did in the preceding snippet was add the @Injectable class decorator on top of the definition of the Car class and provide type annotations for the parameters of its constructor.