<script> var hour, minute, second; //时 分 秒 hour = minute = second = 0; //初始化 var int; function p(s) { return s < 10 ? '0' + s: s; } function reset() { window.clearInterval(int); document.getElementById('timetext').innerHTML = '00:00:00'; hour = minute = second = 0; } function start() { int = setInterval(timer, 1000); } //计时 function timer() { second++; if(second >= 60) { second = 0; minute = minute + 1; } if(minute >= 60) { minute = 0; hour = hour + 1; } document.getElementById('timetext').innerHTML = p(hour)+':'+p(minute)+':'+p(second); } </script>