Constructor method

In JavaScript, a constructor method is used to create and initialize objects.
In object-oriented programming, Constructors are used to define and create objects of a particular class or type.
They are called when you use the new keyword to create an instance of an object.

Syntax:

function ClassName(param1, param2, ...) {
 // Constructor code here
 // Initialize instance properties
 this.param1 = param1;
 this.param2 = param2;
 // ...
}

ClassName is the name of the constructor function.
param1, and param2, are parameters that you can pass to the constructor when creating an instance of the object.
this refers to the newly created instance of the object, and you can use it to set instance properties.

Example:

<!DOCTYPE html>
<html>

<body>

  <script>
    class Employee {
      constructor() {
        this.id = 105;
        this.name = "john";
      }
    }
    var emp = new Employee();
    document.writeln(emp.id + " " + emp.name);
  </script>

</body>

</html>

Output:

105 john

Using super keyword:

super keyword is used to call parent class Constructor.

Example:

<!DOCTYPE html>
<html>

<body>

  <script>
    class CompanyName {
      constructor() {
        this.company = "Quipoin";
      }
    }
    class Employee extends CompanyName {
      constructor(id, name) {
        super();
        this.id = id;
        this.name = name;
      }
    }
    var emp = new Employee(1, "John");
    document.writeln(emp.id + " " + emp.name + " " + emp.company);
  </script>

</body>

</html>

Output:

1 John Quipoin