Learn How to Change the Class Name of an Element with JavaScript

Changing the class name of an HTML element dynamically can greatly enhance the interactivity and responsiveness of a website. This article will guide you through the process of altering class names using JavaScript, giving you the tools to create engaging web experiences.


In the dynamic world of web development, user interactions play a crucial role in enhancing user experiences. JavaScript, a versatile scripting language, allows developers to manipulate HTML elements in real-time. One powerful aspect of this manipulation is the ability to change the class name of an element. This article will walk you through the process of achieving this feat, providing you with the knowledge needed to make your web pages more engaging.

Understanding HTML Classes and JavaScript

Before delving into the technicalities of changing class names with JavaScript, let’s understand the foundation. In HTML, classes are used to apply styles and behaviors to multiple elements at once. By assigning the same class to different elements, you can ensure consistent styling across your website. JavaScript comes into play when you want to change these class names dynamically, based on user actions or other events.

Selecting Elements in JavaScript

To manipulate an element’s class name with JavaScript, you first need to select the element itself. JavaScript offers various methods for selecting elements based on different criteria:

// Selecting an element by ID
const elementById = document.getElementById("elementId");

// Selecting elements by class name
const elementsByClass = document.getElementsByClassName("className");

// Selecting elements with CSS selectors
const elementBySelector = document.querySelector(".selector");

Changing Class Names

Once you’ve selected an element, you can access its className property to change its class name. However, a more modern approach involves using the classList property, which provides methods for adding, removing, and toggling classes.

Adding and Removing Classes

Adding a class to an element is achieved using the classList.add() method. Similarly, the classList.remove() method removes a specified class from an element. These methods are especially useful when you want to apply or remove specific styles or behaviors.

// Adding a class to an element

// Removing a class from an element

Changing Multiple Classes

In some scenarios, you might need to change multiple classes on an element simultaneously. The classList property also offers a replace() method, which allows you to replace one class with another.

// Replacing a class on an element
elementBySelector.classList.replace("oldClass", "newClass");

Best Practices for Class Manipulation

While JavaScript empowers you to manipulate class names, it’s essential to follow best practices:

  • Keep class names descriptive and meaningful to maintain code readability.
  • Separate your styling logic from your JavaScript code by using external CSS files.

Common Use Cases

Understanding how to change class names opens up a world of possibilities:

  • Implementing interactive buttons: Change a button’s class to visually indicate when it’s clicked.
  • Applying dynamic styles: Alter an element’s class based on user interactions to provide instant feedback.

Troubleshooting Class Changes

When working with class changes, it’s not uncommon to encounter issues:

  • Debugging common problems: Troubleshoot issues by checking for typos and syntax errors.
  • Ensuring proper execution: Verify that your JavaScript code runs at the appropriate time during page load.


Incorporating dynamic class changes into your web development toolkit can significantly enhance user experiences. By following the steps outlined in this article, you’ve learned how to manipulate class names using JavaScript. As you experiment and explore this newfound knowledge, you’ll discover endless possibilities for creating engaging and interactive web pages.


Can I change multiple classes simultaneously?

Yes, you can change multiple classes at once using the classList.replace() method.

Do I need to be an expert in JavaScript to implement class changes?

While a basic understanding of JavaScript is beneficial, the provided examples make it accessible to developers of varying skill levels.

What if the class changes don’t seem to take effect?

Double-check your code for any errors, and ensure that your JavaScript code runs at the appropriate time during page load.

Is it recommended to use inline styles alongside class changes?

It’s generally better to separate your styling from your JavaScript logic by using external CSS files.

Where can I learn more about advanced JavaScript techniques?

Explore online resources and tutorials focused on JavaScript to continue enhancing your skills.

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