JavaScript: Introduction to Classes

Classes are used to create objects. Let me try to explain with an example.

class Employee{

  constructor(id, firstName, lastName){

    this.id = id;

    this.firstName = firstName;

    this.lastName = lastName;

  }

}

As you see above snippet, I defined a class Employee, which has 3 properties id, firstName, lastName.

a.   class keyword is used to create a class.

b.   constructor function is used to initialize the properties.

You can define object to the class Employee using new operator, followed by constructor function.

var emp1 = new Employee(1, "Sailaja", "PTR");

HelloWorld.js

class Employee{
  constructor(id, firstName, lastName){
    this.id = id;
    this.firstName = firstName;
    this.lastName = lastName;
  }
}

function print_employee_info(emp){
  console.log("id : " + emp.id);
  console.log("firstName : " + emp.firstName);
  console.log("lastName : " + emp.lastName);
}

var emp1 = new Employee(1, "Sailaja", "PTR");

print_employee_info(emp1);

Output

id : 1

firstName : Sailaja

lastName : PTR   

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