Javascript Introduction
Comments in Javascript
Javascript Variables
Difference between var, let and const in Javascript
Datatypes
Assignment Operators
Logical Operators
Comparison Operators
Actions alert, prompt & confirm

Javascript Flow Control
Conditional Statements in Javascript
Nullish coalescing operator in Javascript
Break and Continue in Javascript
Loops in javascript
for loop in Javascript
while loop

Javascript Functions
Javascript Functions
JavaScript Arrow Function

Javascript Objects
Javascript Objects

Javascript Array
Javascript Arrays

Javascript Error Handling
Error Handling in Javascript

Javascript ES6
Set
Javascript Spread Operator
Rest Parameter in Javascript

Javascript Asynchronous
Javascript Callback Function
Promises in Javascript
Promise Chaining
Async-Await in Javascript

Javascript DOM
DOM Document
DOM Elements
DOM Attributes
DOM Manipulation
DOM Node Lists
Javascript Events
DOM Traversing Elements
DOM EventListener

Javascript Class
Classes in javascript
Class Inheritance

Javascript Design Principles
SOLID - The Single responsibility principle in javascript
SOLID - Open-Closed principle in Javascript

Other Topics
Javascript Hoisting
Filter, Map and Reduce functions in Javascript
Closure in Javascript
Optional chaining operator in Javascript
Consoling in table format in javascript
Fetch API in Javascript
HTML web Storage API
Checking the online or offline status of the browser

Classes in javascript

Published on: July 03, 2021 By T.Andrew Rayan

Classes are used to encapsulate the related data or objects and the code to work on those objects. It may contain functions, objects and variables that are encapsulated to form a class.

The class is identified with the class keyword.

Syntax for declaring a class:

class className {
 // constructors
 // properties and methods
}

Each class can have a constructor, which will be called when we create an object for the class.

Example for class declaration:

class Employee {
 constructor(name, age) {
 this.name = name;
 this.age = age;
 }
}

Here we have create a class named Employee and a constructor which gets name and age as parameter and assigns it to internal class variables name and age identified with this keyword. The this keyword denotes that the variable is the property of that class.

Now lets create a function in the class and work on the properties of the class.

class Employee {
 constructor(name, age) {
 this.name = name;
 this.age = age;
 }
 printName = () => {
    console.log(`Name is ${this.name}`);
 }
 printAge = () => {
    console.log(`Age is ${this.age}`);
 }
}

let employee = new Employee("Andrew",30);
employee.printName();
console.log(employee.age);

Output:

Age is 30

In the above example, we have created a class with 2 properties, name and age which are initialized using constructor. Then we have 2 functions printName and printAge to print the name and age of the employee.

To create an object for the class we use the syntax

new className();

The className should be replaced with the desired class name. To supply values to name and age parameters through constructor we use

let employee = new Employee("Andrew",30);

We had assigned the created object to the variable employee. Now we can call the functions as well as the get the properties inside the class using the employee object.

Classes in javascript

Published on: July 03, 2021 By T.Andrew Rayan

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