Uma boa contagem regressiva de página JS HTML pode ser precisa para segundos, o que é simples, mas prático
<! doctype html> <html> <head> <meta charset = "utf-8"> </adfilge> <body> <div id = "countmsg"> <span id = "t_d"> 00 dias </span> <span id = "t_h"> 00 hours </span> <span iD = "t_m"> segundos </span> </div> <script type = "text/javascript"> function getrtime () {var endtime = new Date ('2014/10/23 10:00:00'); // Prazo var agora tempo = new Date (); var t = endtime.getTime () - nowtime.gettime (); /*var d = math.floor (t/1000/60/60/24); t- = d*(1000*60*60*24); var H = Math.Floor (T/1000/60/60); t- = h*60*60*1000; var m = math.floor (T/1000/60/60); t- = m*60*1000; var s = math.floor (t/1000);*/var d = math.floor (t/1000/60/60/24); var H = Math.Floor (T/1000/60/60%24); var m = math.floor (T/1000/60%60); var s = math.floor (t/1000%60); document.getElementById ("t_d"). innerhtml = d + "dia"; Document.getElementById ("T_H"). Innerhtml = H + "Time"; document.getElementById ("t_m"). innerhtml = m + "minutos"; document.getElementById ("t_s"). INnerHTML = S + "segundos"; } setInterval (getRtime, 1000); </script> </body> </html>