let dots = document.querySelectorAll(".dots > div"); for (let d of dots) { d.onclick = function (event) { if (this.dataset && this.dataset.page) { let switchPage = document.querySelector(this.dataset.page); if (switchPage) { if (!this.classList.contains("active") && !switchPage.classList.contains("active")) { let active = document.querySelector(".dots > .active"); let activePage = document.querySelector(".page.active"); if (active && activePage) { active.classList.remove("active"); activePage.classList.remove("active"); } } this.classList.add("active"); switchPage.classList.add("active"); } } }; }