Optimizing Lottie Animation Preloading with CSS and JavaScript: A Practical Approach

When transitioning from Webflow to a custom HTML, CSS, and JavaScript setup, developers often encounter challenges with smooth animations and performance. One common issue arises when replacing Lottie animations—particularly those that simulate complex effects like 3D rotations—with CSS-driven solutions. A key concern is ensuring that all image frames are preloaded to prevent visual glitches such as blinking or layout shifts during the initial hover.

In this context, I was working on a project that involved recreating a Webflow-based site using fundamental web technologies. The goal was to animate energy cans with a 3D rotation effect triggered on hover. Originally, this was achieved with a Lottie animation, but I aimed to replace it with CSS images for better control and performance. However, I faced difficulties in preloading all image frames efficiently, leading to flickering when the user first interacts with the element.

Despite experimenting with JavaScript solutions—such as pre-running the animation sequence to cache frames—the issue persisted. The challenge lies in ensuring all images involved in the animation are fully loaded before the user initiates interaction, thus maintaining a seamless experience.

Key Insights and Recommendations

• Preloading Image Frames: To achieve smooth hover effects mimicking 3D rotation, preload all required images as soon as the page loads. This can be done by dynamically creating <img> elements or setting background images in CSS and hiding them off-screen until needed.

• Using CSS Sprites or Image Sequences: Combining all frames into a sprite sheet can reduce HTTP requests and facilitate faster rendering. Alternatively, preload individual images with JavaScript’s Image object for control.

• JavaScript Preloading Strategy: Implement a preloader that loads all frames during initial page load. Once loaded, cache references can trigger CSS animations or reveal the fully prepared hover state without blinking.

• Triggering Initial Load: Running a minimal JavaScript animation sequence once after page load can help browser cache all images, reducing flicker during user interaction.

Example Implementation Snippet

“`javascript
// Preload images
const frames = [];
const totalFrames = 10; // replace with your actual frame count

for (let i = 1; i <= totalFrames; i++) {
const img = new Image();
img.src = images/frame_${i}.png; // update path accordingly
frames.push(img);
}

// After all images are loaded