document.addEventListener('DOMContentLoaded', function () { var days = document.querySelector('.days span'); var hour = document.querySelector('.hour'); var min = document.querySelector('.min'); var second = document.querySelector('.second'); var startDate = new Date(2019, 3, 11); days.innerText = Math.floor((new Date(2022, 9, 8) - startDate) / 86400000); countTime(); function countTime() { let today = new Date(); let ms = (today - startDate) % 86400000; hour.innerText = Math.floor(ms / 3600000); min.innerText = Math.floor(ms % 3600000 / 60000); second.innerText = Math.floor(ms % 3600000 % 60000 / 1000); } // setInterval(countTime, 1000); }, false);