MediaWiki:Common.js

/* Any JavaScript here will be loaded for all users on every page load. */

const backToTop = document.getElementById("BackToTop");
if (backToTop) {
  document.addEventListener("scroll", function() {
    const isVisible = window.pageYOffset > 400;
    backToTop.style.opacity = isVisible ? '1' : '0';
  });
  backToTop.addEventListener("transitionstart", function() {
    backToTop.hidden = false;
  });
  backToTop.addEventListener("transitionend", function() {
    if (backToTop.style.opacity == 0) backToTop.hidden = true;
  });
}