The avatar for @gianordoli
Gabriel Gianordoli
Published
Edited
Mar 29, 2021
Importers
3 stars
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setupObserver = (root, rootMargin) => {

const sectionEls = [...root.querySelectorAll('.section')];
const navEls = [...root.querySelectorAll('.nav > a')];
function observerCallback(entries, observer) {
entries.forEach(entry => {
if (entry.isIntersecting) {
const { index } = entry.target.dataset;
toggleNav(navEls, index);
}
})
}
const options = {
root,
rootMargin,
};
const observer = new IntersectionObserver(observerCallback, options);
sectionEls.forEach(el => observer.observe(el));
}
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toggleNav = (navEls, index) => {
navEls.forEach((el, i) => {
if (i === parseInt(index)) {
el.classList.add('active');
console.log(i);
} else {
el.classList.remove('active');
}
});
}
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setupObserver(example1.querySelector('.frame'), rootMarginExample1)
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generate1pxRootMargin = (frameHeight, bottomPerc) => {
let bottom = frameHeight * parseFloat(bottomPerc.slice(0, bottomPerc.indexOf('%'))) * 0.01;
return `${-(frameHeight + bottom)}px 0px ${(bottom + 1)}px 0px`;
}
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rootMarginExample2 = generate1pxRootMargin(500, '-50%')
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setupObserver(example2.querySelector('.frame'), rootMarginExample2)
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