A Better Way to Handle CSS Transitions in JavaScript

Discover a more efficient method to manage CSS transitions with JavaScript that eliminates the need for setTimeout(). Learn how to use transition events to enhance your code!
---

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: Better way to have JavaScript function wait until transition is finished than just setting `setTimeout()` to same as transition-duration?

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
A Better Way to Handle CSS Transitions in JavaScript

When working with JavaScript and CSS, one common challenge developers face is ensuring that the JavaScript logic executes at the right time during CSS transitions. For instance, if you want to change the color of a <span> element when clicked and then revert it back after the transition finishes, relying solely on setTimeout() can feel inefficient and cumbersome. In this guide, we will explore a more effective way to handle this situation using the transitionend event.

The Problem at Hand

Imagine you have a <span> element styled in CSS to change color on a click event. You want it to turn from cyan to green and then back to cyan after the transition effect completes, which is set to a duration of 100ms. Traditionally, developers often use setTimeout() to sync the timeout duration with the transition duration, like so:

[[See Video to Reveal this Text or Code Snippet]]

While this approach works, it isn’t the most efficient or flexible method, mainly because if the transition duration changes, you have to update it in two places: the CSS and the JavaScript.

A More Efficient Solution

Instead of hardcoding a timeout based on the transition duration, we can take advantage of the transitionend event. This event fires when a CSS transition ends, allowing us to execute our JavaScript code precisely when we need it, instead of relying on arbitrary timers.

Step-by-Step Implementation

Here’s how you can use the transitionend event efficiently:

Add an event listener for the click event to change the color to green immediately when clicked.

Use the transitionend event listener to revert the color back to cyan.

Here’s the updated code combining both functionalities:

[[See Video to Reveal this Text or Code Snippet]]

Full Example

Here's how the complete HTML structure with CSS and JavaScript would look using the transitionend approach:

[[See Video to Reveal this Text or Code Snippet]]

Conclusion

Using the transitionend event streamlines your code, making it cleaner and less prone to errors. This method automatically adjusts to any changes in the transition duration defined in your CSS, eliminating redundant code and potential inconsistency. By adopting this approach, you enhance not only your coding efficiency but also the maintainability of your project.

By stepping up from the basic use of setTimeout() to leveraging CSS transition events, you can create more interactive and responsive web applications that feel polished and professional.

If you found this guide helpful, consider sharing it with your fellow developers. Happy coding!