TypeScript - Classes - this keyword - constructors

Now, in the below example, elevation is a protected variable.

class Visakhapatnam extends City{

name = "Visakhapatnam";

protected elevation = 45;

constructor(){

super("Visakhapatnam");

}

}

We can also modify it inside the constructor by using this keyword. 

class Visakhapatnam extends City{

name = "Visakhapatnam";

constructor(){

super("Visakhapatnam");

this.elevation = 45;

}

}

const cityVisakha = new Visakhapatnam();

console.log(cityVisakha);

console.log(cityVisakha.name);

cityVisakha.setType("Town");

console.log(cityVisakha.printType());

console.log(cityVisakha.getElevation());

console.log(cityVisakha);

Now, if i compile:

$ tsc

$

and .. check in the console.  

Console Output:

Visakhapatnam elevation: 45name: "Visakhapatnam"type: "Town"__proto__: City

city-App.ts:138 Visakhapatnam

city-App.ts:109 new type = Town

city-App.ts:113 Town

city-App.ts:140 undefined

city-App.ts:104 45

city-App.ts:141 undefined

city-App.ts:142 Visakhapatnam

We can see, that using the this keyword - the elevation was updated. Note that we cannot update the type using the this keyword. This is because, private properties are not accessible using the this keyword in the child classes.