我简直无法忍受setTimeout(...,1000)并期望它正好是 1,000 毫秒。新闻快讯：事实并非如此。事实上，根据您的系统，它可能是 992 到 1008 之间的任何值，并且该差异会累加。
我将向您展示一个带有增量计时的可暂停计时器，以确保准确性。导致此结果不准确的唯一方法是您在中间更改计算机的时钟。
function startTimer(seconds, container, oncomplete) {
var startTime, timer, obj, ms = seconds*1000,
display = document.getElementById(container);
obj = {};
obj.resume = function() {
startTime = new Date().getTime();
timer = setInterval(obj.step,250); // adjust this number to affect granularity
// lower numbers are more accurate, but more CPU-expensive
};
obj.pause = function() {
ms = obj.step();
clearInterval(timer);
};
obj.step = function() {
var now = Math.max(0,ms-(new Date().getTime()-startTime)),
m = Math.floor(now/60000), s = Math.floor(now/1000)%60;
s = (s < 10 ? "0" : "")+s;
display.innerHTML = m+":"+s;
if( now == 0) {
clearInterval(timer);
obj.resume = function() {};
if( oncomplete) oncomplete();
}
return now;
};
obj.resume();
return obj;
}
并用它来启动/暂停/恢复：
// start:
var timer = startTimer(5*60, "timer", function() {alert("Done!");});
// pause:
timer.pause();
// resume:
timer.resume();
