Question

目前正在处理一个页面上需要两个计时器的项目。定时器需要有一个开始按钮，两者都有不同的定时（即timer1持续10秒，timer2持续20）。这是我正在使用的脚本，但我不知道如何复制计时器并让每个计时器独立工作。

是否有人可以轻松地将此脚本更改为两个定时器的功能？

<html>
<head>
<script language="JavaScript" type="text/javascript">
    var interval;
    var minutes = 0;
    var seconds = 10;

    function countdown(element) {
        interval = setInterval(function(timer) {
            var el = document.getElementById(element);
            if(seconds == 0) {
                if(minutes == 0) {
                    (el.innerHTML = "STOP!");     

                    clearInterval(interval);
                    return;
                } else {
                    minutes--;
                    seconds = 60;
                }
            }
            if(minutes > 0) {
                var minute_text = minutes + (minutes > 1 ? ' minutes' : ' minute');
            } else {
                var minute_text = '';
            }
            var second_text = seconds > 1 ? '' : '';
            el.innerHTML = minute_text + ' ' + seconds + ' ' + second_text + '';
            seconds--;
        }, 1000);
    }
var start = document.getElementById('start');

start.onclick = function(timer) {
    if (!interval) {
        countdown('countdown');
    }
}

</script>
</head>

<body>
<div id='countdown'></div>
<input type="button" onclick="countdown('countdown');this.disabled = true;" value="Start" />
</body>
</html>

Answer 1

您正在做的一些事情阻止您扩展代码。如果你想要一个可重复使用的计时器，你不能硬设置它将使用的变量。首先要摆脱顶部的三个变量，并在函数范围内重新创建它们。

这样，每次调用函数时，都会为其执行创建一组新的变量。

分钟和秒可能最好作为参数传递，间隔应在函数范围内定义。

其次，您将内置的Click处理程序设置为BOTH。摆脱其中一个（最好摆脱内联版本）。

然后，您有一个计时器变量作为click处理程序和setInterval的参数但从未使用过。该变量将被设置为事件处理程序上的click事件（并且再次未被使用），并且将在setInterval上未定义。所以他们真的不应该在那里。

性能问题，您可能想要了解的是，您每隔一秒钟就会对计数器执行DOM查找。你应该在每个函数调用时得到它一次并缓存它。

此时，你的功能看起来或多或少就像这样

function countdown(element, minutes, seconds) {
    // Fetch the display element
    var el = document.getElementById(element);

    // Set the timer
    var interval = setInterval(function() {
        if(seconds == 0) {
            if(minutes == 0) {
                (el.innerHTML = "STOP!");     

                clearInterval(interval);
                return;
            } else {
                minutes--;
                seconds = 60;
            }
        }

        if(minutes > 0) {
            var minute_text = minutes + (minutes > 1 ? ' minutes' : ' minute');
        } else {
            var minute_text = '';
        }

        var second_text = seconds > 1 ? '' : '';
        el.innerHTML = minute_text + ' ' + seconds + ' ' + second_text + '';
        seconds--;
    }, 1000);
}

您的设置或多或少都是这样的

//Start as many timers as you want

var start1 = document.getElementById('timer1');
var start2 = document.getElementById('timer2');

start1.onclick = function() {
    countdown('countdown1', 0, 15);
}

start2.onclick = function() {
    countdown('countdown2', 0, 10);
}

当然，您需要额外的按钮和计数器

<div id='countdown1'></div>
<div id='countdown2'></div>
<input id="timer1" type="button" value="Start timer 1" />
<input id="timer2" type="button" value="Start timer 2" />

工作示例：http://codepen.io/anon/pen/Jmpcq/?editors=101

- 注意：对于精确的计时器，setInterval()可能不是一个好的选择，因为不保证精确的间隔，并且它可能会在一段时间后延迟。对于精确时间至关重要的应用，还有其他方法（例如https://sitepoint.com/creating-accurate-timers-in-javascript＆amp; https://html5rocks.com/en/tutorials/webperformance/usertimin），感谢@KaiKarver在评论中指出。

Answer 2

var interval;

var countdown1 = {
    minutes:0,
    seconds: 10
};

var countdown2 = {
    minutes:0,
    seconds: 2
}

function countdown(element) {
    alert(element);
    var cd;
    element === 'countdown1' ? cd = countdown1 : cd = countdown2;
    interval = setInterval(function(timer) {
        var el = document.getElementById(element);
        if(cd.seconds == 0) {
            if(cd.minutes == 0) {
                (el.innerHTML = "STOP!");     

                clearInterval(interval);
                return;
            } else {
                cd.minutes--;
                cd.seconds = 60;
            }
        }
        if(cd.minutes > 0) {
            var minute_text = cd.minutes + (cd.minutes > 1 ? ' minutes' : ' minute');
        } else {
            var minute_text = '';
        }
        var second_text = seconds > 1 ? '' : '';
        el.innerHTML = minute_text + ' ' + cd.seconds + ' ' + second_text + '';
        cd.seconds--;
    }, 1000);
}
var start = document.getElementById('start');


 <div id='countdown'></div>
 <input type="button" onclick="countdown('countdown1');this.disabled = true;" value="Start" />
 <div id="countdown1"></div>

 <input type="button" onclick="countdown('countdown2');this.disabled = true;" value="Start" />
 <div id="countdown2"></div>

小提琴：http://jsfiddle.net/dn3hJ/

Answer 3

很长，但有效

let d = document,
    id = 'getElementById',
    time = {
//Multiple Timers
//[current time, time setting, (pause/running), HTML section#timer]
      timer1: ['0:10', '0:10', 0, d[id]('timer1')],
      timer2: ['2:30', '2:30', 0, d[id]('timer2')],
      timer3: ['5:00', '5:00', 0, d[id]('timer3')],


//Manage Timer Functions
      reset: function(t) {time[t][0] = time[t][1];},
      pause: function(t) {time[t][2] = 0;time.state(t,'pause');time.button(t,'resume');},
      resume: function(t) {time[t][2] = 1;time.state(t,'running');time.button(t,'pause');},
      set: function(t,s) {time[t][0] = s; time[t][1] = s;},
      state: function(t,s) {time[t][3].setAttribute('state',s);},
      button: function(t,s) {time[t][3].querySelector('div').innerHTML = s;},
      cancel: function(t) {time[t][2] = 0;time.reset(t);time.state(t,'');time.button(t,'start');time.setTimer(t);},
      start: function(t) {time.reset(t);time[t][2] = 1;time.state(t,'running');time.button(t,'pause');},
      getTimers: function() {return Object.keys(time).filter(function (n) {return n.indexOf("ti")==0;});},
      setTimer: function(t) {time[t][3].querySelector('span').innerHTML = time[t][0]},
      setTimers: function(x) {
        let times = time.getTimers();
        for (var i=0,t;i<times.length;i++) {t=times[i];
              if(time[t][2]||x){time[t][3].querySelector('span').innerHTML = time[t][0]}
        }
  },
};

//handle seconds passed
function convertSeconds(s=0) {return new Date(s*1000).toISOString().substr(11,8).replace(/^(00:0(?=[1-9])|00:|0)/gm, '')}
function toSeconds(t) {t=t.split(':').reverse();return (t[2]*3600||0)+(t[1]*60||0)+t[0]*1||0;}

//set HTML times onLoad
time.setTimers(1)


function runTimer(times){times = time.getTimers();time.setTimers();
    function run(t,s,l){if(t&&t[2]){s=toSeconds(t[0]);t[0]=s?convertSeconds(s-1):'00:00'&&(time.cancel(l));}}
    for (var i=0,t;i<times.length;i++) {run(time[times[i]],'',times[i])}
}

//run timer every second reguardless of whether timer is paused or running
setInterval(runTimer, 1000)

body {
  background: #e6e9f0;
  user-select: none;
  font-family: "SF Pro Display", Helvetica Neue, Arial, Helvetica, Geneva, sans-serif;
  font-size: 14px;
}
div, span {display: inline-block;}
span {min-width: 60px;}
#time > section {
  padding: 10px 20px;
  background: white;
  margin: 10px;
  border-radius: 4px;
  transition: .15s ease-in-out 0s;
  text-transform: capitalize;
}
#time > section:hover {box-shadow: 0px 0px 0px 2px #A8D1FD;}
#time > section > div{text-shadow: 0 1px 1px rgba(0,0,0,0.3);transition: .1s ease-in-out 0s;}
#time > section > div:nth-of-type(2){background: #cfd3dd;opacity: 1;}
#time > section[state=""] > div:nth-of-type(2) {opacity: 0;}
#time > section > div{
  background: #368ad2;
  color: white;
  padding: 6px 10px;
  margin: 0 5px;
  min-width: 50px;
  text-align: center;
  border-radius: 4px;
}

<section id="time">
  <section id="timer1" state="">
    <span>0:00</span>
    <div onClick="time[this.innerHTML]('timer1')">start</div>
    <div onClick="time.cancel('timer1')">cancel</div>
  </section>
  <section id="timer2" state="">
    <span>0:00</span>
    <div onClick="time[this.innerHTML]('timer2')">start</div>
    <div onClick="time.cancel('timer2')">cancel</div>
  </section>
  <section id="timer3" state="">
    <span>0:00</span>
    <div onClick="time[this.innerHTML]('timer3')">start</div>
    <div onClick="time.cancel('timer3')">cancel</div>
  </section>
</section>

一页上有多个倒计时器

3 个答案: