How To Use Classes in JavaScript

Until recently, the concept of classes didn’t exist in JavaScript. The syntax element was introduced in 2015. Having said that, JS classes don’t have as many distinct properties as those in Java do.

How To Use Classes in JavaScript

In this post, we’ll discuss what you can do with classes in JavaScript, how they are different from Java ones, and what the best practices for handling them are.

What Is a Class in JavaScript?

Classes were introduced to JS to improve the readability of the code and facilitate the process of integrating Java code into JavaScript. By nature, classes are functions – however, you don’t need to type function() in to initiate it. Similarly to other functions, initiating a class will return the ‘[[Prototype]]’ function.

JavaScript developers can turn classes into construction instances by attaching the new keyword to it. Other operations classes enable are:

  • Using default or creating custom methods;
  • Being extended as object blueprints;
  • Inheriting the methods from a different class;
  • Applying get and set.

Advantages of JavaScript Classes

Although web developers are not particularly fond of JS classes due to their pseudo nature and limited functionality, they offer a pack of benefits software engineers can’t afford to ignore.

Here are the advantages of using classes in JavaScript:

  • Facilitates the integration of Java code into JavaScript;
  • The ability to leverage on the potential of object-oriented programming;
  • The code will be encapsulated;
  • Increased speed of creating new objects.

Thus, manipulating functions using the class keyword de-clutters the code and helps create objects with shared inheritance.

Classes in JavaScript vs Java

In case you are familiar with the concepts of classes in Java but are new to their functionality in JS, understanding the difference between the two is a solid starting point. Here’s a comparison table that’ll help draw the distinction between the two types of classes.

JavaScript Java
You can assign class properties – methods, properties, or field. Java classes don’t have the properties of an object.
Does not provide any guarantees Provide guarantees that the methods will be inherited by the next function
Classes rely on prototype-based inheritanceClasses are the groundwork of class-based inheritance
Add ‘syntax sugar’ to the languageOne of the key concepts of language’s object-orientedness.

Essentially, JS classes are nothing but objects that are slightly easier to handle. If you have Java background, don’t expect to run class-based operation in JS the way you used to in Java.

How to Handle JavaScript Classes?

How to Handle JavaScript Classes?

If you want to update the syntax of your code from functions to classes, learn how to manage, define, and delete a class. Here’s a full guide on JavaScript classes.

Defining a class

Where you would use function() earlier, type in the class keyword. Specify the properties of a class in a constructor and define the parameters of the function using this keyword. Using class instead of function() helps be more straightforward about the objective of the function.

Assigning methods to the class

The class syntax makes handling methods considerably easier since you don’t have assign methods to the prototype. Instead, a developer can use the method definition shorthand. You can create new instances and keywords and assign values to them. To see more information on the object, use console.log().

The downside of assigning methods to classes is having to lose clarity along the way. During the development process, you need to remember that the methods will still be assigned to prototypes, not to the original object.

Extending classes

Being able to assign class properties to object blueprints is a feature JS devs should take advantage of. This way, you can increase cost reusability and manage objects more efficiently.

The most common way to create a new function with the properties of an existing one is by running a call() method and assigning the inheritance of a parent object over to a new one.

Another way is to use the super keyword instead. To establish the relationship between functions, use extend.

Using ‘get and ‘set’ keywords

Using getters and setter is a common practice that offers developers more flexibility. To add a 'get' or 'set' to a property, enter the keywords inside the constructor(). Remember that there’s no need to use parentheses after getters and setters even if they are methods.

Also, get and set values can’t be the same as the property name. You can use the _ character to differentiate the two.

Writing in ‘use strict’. 

The strict mode is mandatory when it comes to working with classes. Essentially, it means you have to declare variables before using it. To write in the strict mode, add use strict at the beginning of the script. The statement has a global scope – it applies to all lines of code.


In JavaScript, classes are not that big of a deal. You can get by without them, and the functionality of an application will not change drastically. The primary objective the keyword achieves is to speed up the development process and adopt some (not all) promising properties of Java classes.

The good news is, mastering JS classes is easy and requires little effort. In a month of extensive coding, you will get fully used to declaring classes and will manage them in the blink of an eye.

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