<script type="text/javascript">function startTime(){//获取当前系统日期var today=new Date()var h=today.getHours()var m=today.getMinutes()var s=today.getSeconds()//调用checkTime（）函数，小于十的数字前加0m=checkTime(m)s=checkTime(s)//s设置层txt的内容document.getElementById('txt').innerHTML=h+":"+m+":"+s//过500毫秒再调用一次t=setTimeout('startTime()',500)//小于10，加0function checkTime(i){if(i<10){i="0"+i}return i}}</script>