Why Optimize Animations?
Poorly optimized animations can slow down your app, causing:
Janky transitions
High CPU & memory usage
Low frame rates (FPS drops)
By optimizing animations, you ensure smooth user experience (UX) and better app responsiveness.
1️⃣ Use One-Time Binding for Static Data
When using animations on elements with static content, use one-time binding (::) to prevent unnecessary re-renders.
Example
<p>{{::message}}</p>
Why? AngularJS won’t re-evaluate message once it’s set, reducing the digest cycle overhead.
2️⃣ Minimize the Number of Watches
Animations should not trigger unnecessary $digest cycles.
Example: Avoid Heavy $watch
$scope.$watch('someValue', function (newVal) {
console.log('Change detected');
});
Solution: Use $watchCollection() only for arrays/objects instead of deep-watching.
3️⃣ Use CSS3 Animations Instead of JavaScript
CSS3 animations are hardware-accelerated, whereas JavaScript-based animations rely on the CPU.
Example: Optimized Fade-In
.fade-animation {
opacity: 0;
transition: opacity 0.5s ease-in-out;
}
.fade-animation.ng-enter {
opacity: 1;
}
Why? CSS3 animations run on the GPU, making them smoother and faster.
4️⃣ Enable will-change for GPU Optimization
If an element is animated frequently, tell the browser in advance to optimize it.
Example: Adding will-change
.animated-box {
will-change: transform, opacity;
}
Why? The browser prepares the element for animations, making them more efficient.
5️⃣ Use requestAnimationFrame() for JS Animations
If you’re using JavaScript to animate, avoid $timeout() and $interval(). Instead, use requestAnimationFrame().
Example: Using requestAnimationFrame()
function animateElement() {
requestAnimationFrame(function () {
element.style.transform = 'translateX(100px)';
});
}
Why? This ensures animations sync with screen refresh rates (~60FPS), preventing lag.
6️⃣ Use track by in ng-repeat
When animating list items, use track by to avoid unnecessary re-rendering.
Example
<div ng-repeat="item in items track by item.id">
{{item.name}}
</div>
Why? Prevents AngularJS from rebuilding the entire DOM, improving performance.
7️⃣ Optimize $animate Usage
Avoid using $animate for small UI changes and use CSS transitions instead.
Example: Use $animate Only When Necessary
$animate.addClass(element, 'fade-in').then(function () {
console.log('Animation completed');
});
Why? Reduces overhead and improves performance.
8️⃣ Avoid Animating Large Elements
Animating large elements (like full-screen modals) is resource-intensive.
Solution: Use position: fixed Instead of position: absolute
.modal {
position: fixed;
transform: translateY(-100%);
}
Why? Fixed elements don’t trigger layout recalculations, making animations smoother.
9️⃣ Reduce Layout Thrashing
Avoid causing unnecessary reflows (DOM recalculations) by batching style changes.
BAD: Causes Reflow on Each Line
element.style.width = "100px";
element.style.height = "200px";
element.style.margin = "10px";
GOOD: Use classList.add()
element.classList.add('resized');
Optimized CSS
.resized {
width: 100px;
height: 200px;
margin: 10px;
}
Why? Reduces browser repaints, making animations smoother.