倒数计时器在刷新时再次重新加载答案

【问题标题】：countdown timer reloading again on refreshing倒数计时器在刷新时再次重新加载
【发布时间】：2015-08-10 11:23:19
【问题描述】：

javascript 中的倒数计时器代码。但是刷新页面时它会再次重新启动。我希望计时器即使重新启动也应该继续。

帮我解决这个问题，因为我是初学者，这是我的第一个应用程序，我需要您提供一些详细信息。

`
<body>
<div id="divCounter"></div>
<script type="text/javascript">

var hoursleft = 0;
var minutesleft = 35;           // you can change these values to any value greater than 0
var secondsleft = 0;

var finishedtext = "Countdown finished!" // text that appears when the countdown reaches 0
var end = new Date();

end.setMinutes(end.getMinutes()+minutesleft);
end.setSeconds(end.getSeconds()+secondsleft);


if(localStorage.getItem("counter")){

    var value = localStorage.getItem("counter");

}else{
  var value = 0;
}


var counter = function (){


    var now = new Date();
var diff = end - now;
diff = new Date(diff);

var sec = diff.getSeconds();
var min = diff.getMinutes();

if (min < 10){
    min = "0" + min;
}
if (sec < 10){
    sec = "0" + sec;
}

if(now >= end){
    clearTimeout(timerID);
    document.getElementById('divCounter').innerHTML = finishedtext;
}
else{
    var value = min + ":" + sec;
//document.getElementById('divCounter').innerHTML = min + ":" + sec;
localStorage.setItem("counter", JSON.stringify(value));
}      

 // timerID = setTimeout("cd()", 1000);
// value = JSON.parse(localStorage.getItem("counter"));
//$('#divCounter').append(value);
document.getElementById('divCounter').innerHTML = value; 
 }





 var interval = setInterval(function (){counter();}, 1000);
 </script>
 </body>
 `

【问题讨论】：

标签： javascript php web-applications countdowntimer web-application-design

【解决方案1】：

你想要的任何时间的倒计时。刷新页面时它不会重新启动。

<body>
<div id="divCounter"></div>


<script>
//var hoursleft = 0;
var minutesleft = 0; //give minutes you wish
var secondsleft = 30; // give seconds you wish
var finishedtext = "Countdown finished!";
var end1;
if(localStorage.getItem("end1")) {
end1 = new Date(localStorage.getItem("end1"));
} else {
end1 = new Date();
end1.setMinutes(end1.getMinutes()+minutesleft);
end1.setSeconds(end1.getSeconds()+secondsleft);

}
var counter = function () {
var now = new Date();
var diff = end1 - now;

diff = new Date(diff);

var milliseconds = parseInt((diff%1000)/100)
    var sec = parseInt((diff/1000)%60)
    var mins = parseInt((diff/(1000*60))%60)
    //var hours = parseInt((diff/(1000*60*60))%24);

if (mins < 10) {
    mins = "0" + mins;
}
if (sec < 10) { 
    sec = "0" + sec;
}     
if(now >= end1) {     
    clearTimeout(interval);
   // localStorage.setItem("end", null);
     localStorage.removeItem("end1");
     localStorage.clear();
    document.getElementById('divCounter').innerHTML = finishedtext;
     if(confirm("TIME UP!"))
     window.location.href= "timeup.php";
} else {
    var value = mins + ":" + sec;
    localStorage.setItem("end1", end1);
    document.getElementById('divCounter').innerHTML = value;
}
}
var interval = setInterval(counter, 1000);
</script>
</body>

【讨论】：

【解决方案2】：

您需要将计时器值存储为 cookie，

刷新后，检查cookie是否被设置，如果是，获取值并将其设置为你的定时器的初始时间，否则从 0 开始

【讨论】：

【解决方案3】：

您在这里要做的是设置倒计时的日期/时间并获取当前用户的日期/时间，然后计算倒计时的差异。

以下内容将帮助您朝着正确的方向前进：

var date  = new Date(Date.UTC(2015, 5, 28, 12, 0, 0));
var now   = new Date();
var diff  = date.getTime()/1000 - now.getTime()/1000;

【讨论】：

【解决方案4】：

虽然您从本地存储中读取 value 变量，但实际上并没有将 end 和 now time 设置为它们的旧值，因此它们正在被重置，同时也重置了 value 变量。您还应该将这些值存储在内存中，并在刷新页面时加载它们。

【讨论】：

如何将这些值存储在内存中并在我刷新页面时加载它们。请解释一下，否则给我链接，我将从那里学习
@SMadhu 我上传了一个新答案 - 你可以从那里复制代码
谢谢它正在工作，但是当我想再试一次而不是时间时，我得到“NaN：NaN”。如何重置计时器？
使用这个 - localStorage.setItem("end", null)

【解决方案5】：

这是完成的、功能齐全的优化代码。它现在应该可以工作了！

<body>
<div id="divCounter"></div>
<script>
var hoursleft = 0;
var minutesleft = 35;
var secondsleft = 0; 
var finishedtext = "Countdown finished!";
var end;
if(localStorage.getItem("end")) {
    end = new Date(localStorage.getItem("end"));
} else {
    end = new Date();
    end.setMinutes(end.getMinutes()+minutesleft);
    end.setSeconds(end.getSeconds()+secondsleft);
}
var counter = function () {
    var now = new Date();
    var diff = end - now;
    diff = new Date(diff);
    var sec = diff.getSeconds();
    var min = diff.getMinutes(); 
    if (min < 10) {
        min = "0" + min;
    }
    if (sec < 10) { 
        sec = "0" + sec;
    }     
    if(now >= end) {     
        clearTimeout(interval);
        localStorage.setItem("end", null)
        document.getElementById('divCounter').innerHTML = finishedtext;
    } else {
        var value = min + ":" + sec;
        localStorage.setItem("end", end);
        document.getElementById('divCounter').innerHTML = value;
    }
}
var interval = setInterval(counter, 1000);
</script>
</body>

【讨论】：