What is the value of unassigned properties of an object?

If you do not assign any value to a property, then the value is undefined.

HelloWorld.js

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

var emp = new Employee();

console.log(emp.firstName + " : " + emp.lastName);

Output

undefined : undefined

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