&#106avascript倒计时器 - 采用系统时间自校验

&#106avascript倒计时器 - 采用系统时间自校验(3) }

// 倒计时函数
function onTimer()
{

if (start == finish)
{
  window.clearInterval(timer);
  alert("time is up!");
  return;
}

var hms = new String(start).split(":");
var ms = new Number(hms[3]);
var s = new Number(hms[2]);
var m = new Number(hms[1]);
var h = new Number(hms[0]);
 
ms -= 10;
if (ms < 0)
{
  ms = 90;
  s -= 1;
  if (s < 0)
  {
    s = 59;
    m -= 1;
  }
 
  if (m < 0)
  {
    m = 59;
    h -= 1;
  }
}

var ms = ms < 10 ? ("0" + ms) : ms;
var ss = s < 10 ? ("0" + s) : s;
var sm = m < 10 ? ("0" + m) : m;
var sh = h < 10 ? ("0" + h) : h;

start = sh + ":" + sm + ":" + ss + ":" + ms;
clock.innerText = start;

// 清除上一次的定时器
window.clearInterval(timer);

// 自校验系统时间得到时间差, 并由此得到下次所启动的新定时器的时间nextelapse
counter++;
var counterSecs = counter * 100;
var elapseSecs = new Date().valueOf() - startTime;
var diffSecs = counterSecs - elapseSecs;
nextelapse = normalelapse + diffSecs;
diff.value = counterSecs + "-" + elapseSecs + "=" + diffSecs;
next.value = "nextelapse = " + nextelapse;
if (nextelapse < 0) nextelapse = 0;

// 启动新的定时器
timer = window.setInterval("onTimer()", nextelapse);
}
</script>