Interface

As we start building complex apps, there will be a common need for a certain type of structure to be repeated throughout the app, which follows certain rules. This is where an interface comes into the picture. Interfaces provide structural subtyping or duck typing to check the type and shape of entities.

For instance, if we are working with an app that deals with cars, every car will have a certain common structure that needs to be adhered to when used within the app. Hence we create an interface named ICar. Any class working with cars will implement this interface as follows:

Interface ICar { 
  engine : String; 
  color: String; 
  price : Number; 
} 

class CarInfo implements ICar{ 
  engine : String; 
  color: String; 
  price : Number; 

  constructor(){ /* ... */} 
}