- Classes in TypeScript is similar to that of most of the classes in other languages.
- Classes are implemented in JavaScript as methods in the compiled .js code.
- Classes have Constructors and new key word to declare an Object in TypeScript.
Example of Simple Class, data members and type creation in TypeScript

Methods in Classes
- Just like we data members, we have member functions as well in TypeScript.
- We can define data type of parameters and return type in these methods.
Constructors
- Constructors in TypeScript can be create using keyword constructor()
- We can only have one constructor in TypeScript
- Constructors can be parameterized as well as empty.
class Person{
private firstName : String;
private lastName : String;
public age : number;
constructor(){
this.firstName = "";
this.lastName = "";
}
public setName(firstName : String, lastName : String){
this.firstName = firstName;
this.lastName = lastName;
}
}
var aPerson : Person= new Person(); //Declaring a variable of Type Person
aPerson.setName("Tyson","Gill")
aPerson.age = 70;
console.log(aPerson);

After compilation the above code is converted into JavaScript and it looks like this :
