PHP精确到毫秒秒杀倒计时实例详解

// 注意php的时间是以秒算。js的时间以毫秒算 
// 设置时区 
date_default_timezone_set('PRC'); 
//配置每天的活动时间段 
$starttimestr = date('Y-m-d H:i:s', strtotime(date('Y-m-d'))); 
$endtimestr = date('Y-m-d H:i:s', strtotime(date('Y-m-d', strtotime('+1 day')))); 
$starttime = strtotime($starttimestr); 
$endtime = strtotime($endtimestr); 
$nowtime = time(); 
if ($nowtime < $starttime) { 
  exit("活动还没开始,活动时间是{$starttimestr}至{$endtimestr}"); 
} 
if ($endtime >= $nowtime) { 
  $lefttime = $endtime - $nowtime; //实际剩下的时间（秒） 
} else { 
  $lefttime = 0; 
  exit("活动已经结束！"); 
}

var runtimes = 0; 
function GetRTime() { 
  var lefttime = < ?php echo $lefttime; ? >  1000 - runtimes  1000; 
      if (lefttime >= 0) { 
    var nD = Math.floor(lefttime / (1000  60  60  24)) % 24; 
    var nH = Math.floor(lefttime / (1000  60  60)) % 24; 
    var nM = Math.floor(lefttime / (1000  60)) % 60; 
    var nS = Math.floor(lefttime / 1000) % 60; 
    document.getElementById("RemainD").innerHTML = nD; 
    document.getElementById("RemainH").innerHTML = nH; 
    document.getElementById("RemainM").innerHTML = nM; 
    document.getElementById("RemainS").innerHTML = nS; 
    if (lefttime == 5  60  1000) { 
      alert("还有五分钟！"); 
    } 
    runtimes++; 
    setTimeout("GetRTime()", 1000); 
  } else { 
    alert('活动结束了！'); 
    location.reload(); 
  } 
} 
var Num = 0; 
onload = function() { 
  Refresh(); 
  setInterval("Refresh();", 100); 
  GetRTime(); 
} 
function Refresh() { 
  if (Num < 10) { 
    document.getElementById("RemainL").innerHTML = Num; 
    Num = Num + 1; 
  } else { 
    Num = 0; 
  } 
}