Effective Strategies for Managing Preloaded Animation Frames in Custom CSS and JavaScript

In the process of recreating a dynamic website feature outside of platforms like Webflow, developers often encounter challenges with smooth animations and preloading assets. One such challenge involves replacing a Lottie animation with CSS and JavaScript while ensuring that all image frames are preloaded for seamless interactions.

A common scenario involves creating a hover effect—such as a 3D rotation of objects like energy cans—using a sequence of images. When these images are not preloaded properly, the animation tends to lag or cause unwanted visual glitches like blinking or layout shifts during the initial hover. This diminishes the user experience and can make the site look less polished.

Attempting to preload individual image frames using JavaScript can help, but sometimes it doesn’t fully resolve the issue. For example, initializing the animation on page load or before user interaction—by running the animation once during page load—may still result in flickering if the images haven’t been cached by the browser.

To effectively preload image sequences for CSS-based animations, consider the following strategies:

1. Preload Images Explicitly

Create a JavaScript image preloading routine that loads all frames into the browser cache before any interaction takes place. This can be done using JavaScript like so:

“`javascript
const imageFrames = [
‘frame1.png’,
‘frame2.png’,
// Add all frames here
];

imageFrames.forEach(src => {
const img = new Image();
img.src = src;
});
“`

Executing this loop on page load ensures that all frames are retrieved from the server and stored in the cache.

2. Use a Hidden Container for Preloading

To further guarantee assets are cached, append the images to a hidden, off-screen container in your HTML:

“`html

“`

And in JavaScript:

“`javascript
const preloadContainer = document.createElement(‘div’);
preloadContainer.style.display = ‘none’;

imageFrames.forEach(src => {
const img = document.createElement(‘img’);
img.src = src;
preloadContainer.appendChild(img);
});

document.body.appendChild(preloadContainer);
“`

3. Trigger Preloading Early

Ensure that the preloading script runs as early as possible—preferably before the user interacts with the