xarxaprod-wp-theme/js/scrollposition.js

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JavaScript
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// https://css-tricks.com/styling-based-on-scroll-position/
// script to detect the scroll position and then call for it in css
// The debounce function receives our function as a parameter
const debounce = (fn) => {
// This holds the requestAnimationFrame reference, so we can cancel it if we wish
let frame;
// The debounce function returns a new function that can receive a variable number of arguments
return (...params) => {
// If the frame variable has been defined, clear it now, and queue for next frame
if (frame) {
cancelAnimationFrame(frame);
}
// Queue our function call for the next frame
frame = requestAnimationFrame(() => {
// Call our function and pass any params we received
fn(...params);
});
}
};
// Reads out the scroll position and stores it in the data attribute
// so we can use it in our stylesheets
const storeScroll = () => {
document.documentElement.dataset.scroll = window.scrollY;
}
// Listen for new scroll events, here we debounce our `storeScroll` function
document.addEventListener('scroll', debounce(storeScroll), { passive: true });
// Update scroll position for first time
storeScroll();