$(window).on("load", function() { /* load timer */ window.setInterval(function() { var time = $("#timer").text(); var t = time.split(":").map(t => parseInt(t)); t[2] -= 1; if (t[2] < 0) { t[2] = 59; t[1] -= 1; } if (t[1] < 0) { t[1] = 59; t[0] -= 1; } if (t[0] < 0) { t[0] = 0; t[1] = 0; t[2] = 0; } $("#timer").text((new Date('December 17, 1995 ' + t.join(':'))).toLocaleTimeString('default', { hour: '2-digit', minute: '2-digit', second: '2-digit' })); }, 1000); });