Vanilla Javascript Check If Element Has Class

Vanilla Javascript Check If Element Has Class

3 min read Jun 20, 2024
Vanilla Javascript Check If Element Has Class

Vanilla JavaScript: Checking if an Element Has a Class

In this article, we'll delve into the fundamental method of verifying if a specific HTML element possesses a particular class using plain JavaScript, without relying on external libraries like jQuery.

Understanding the Concept

Every HTML element can be assigned one or more classes, acting as labels that allow you to group and style elements with shared properties. JavaScript provides several ways to query and manipulate these classes, and checking for their presence is a crucial task in many web development scenarios.

The classList Property

The most straightforward approach is using the classList property, available on all HTML elements. It offers a collection of methods for interacting with classes, including:

  • contains(className): This method takes a string representing the class name and returns true if the element has that class, otherwise false.

Example:

const myElement = document.getElementById('myElement');

if (myElement.classList.contains('active')) {
  console.log("The element has the 'active' class.");
} else {
  console.log("The element does not have the 'active' class.");
}

Using the className Property

While less modern, the className property offers an alternative way to check for classes. It returns a string containing all the classes assigned to the element, separated by spaces.

Example:

const myElement = document.getElementById('myElement');

if (myElement.className.includes('active')) {
  console.log("The element has the 'active' class.");
} else {
  console.log("The element does not have the 'active' class.");
}

This approach relies on string manipulation, which can be less efficient than using the classList methods.

Considerations

  • Performance: While both methods work, classList.contains() is generally considered more efficient for checking class presence.
  • Specificity: Keep in mind that the classList and className methods work on the element's own classes, not those inherited from parent elements.

Conclusion

By utilizing the classList.contains() or className.includes() methods, you can reliably determine if an element has a particular class within your JavaScript code. This simple yet essential technique empowers you to create dynamic and interactive web applications.