How can you detect when an element becomes fully visible?
const observer = new IntersectionObserver((entries) => {
entries.forEach(entry => {
if (entry.intersectionRatio === 1) {
console.log('Element is fully visible');
trackFullVisibility(entry.target);
}
});
}, {
threshold: 1.0
});
Using Intersection Observer with a threshold of 1.0 is the most reliable way to detect when an element becomes fully visible because: 1) It triggers the callback only when 100% of the target element is visible in the root, 2) It handles all edge cases and scroll directions automatically, 3) It's more performant than calculating visibility manually, 4) It works consistently across different viewport sizes and devices. The code demonstrates this by checking for an intersectionRatio of 1, indicating complete visibility.