用JS写了一个30分钟倒计时器的实现示例
作者：巨輪
本文主要介绍了用JS写了一个30分钟倒计时器的实现示例，文中通过示例代码介绍的非常详细，具有一定的参考价值，感兴趣的小伙伴们可以参考一下
前端页面倒计时功能在很多场景中会用到，如很多秒杀活动等，本文主要介绍了用JS写了一个30分钟倒计时器的实现示例，感兴趣的可以了解一下
<!DOCTYPE HTML>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html;charset=utf-8"/>
<title>Countdown Timer</title>
<style type="text/css">
input{
padding-bottom: 0px;
padding-top: 0px;
border-top-width: 0px;
border-left-width: 0px;
border-right-width: 0px;
font-size: 20px;
width:100%;
}
</style>
</head>
<body>
<span id="numbers" style="white-space:nowrap;"></span>
<table id="table1" >
<tr>
<td style="background-color:rgb(41, 74, 155);padding:3px;"></td>
<td></td>
</tr>
<tr>
<td style="width:100%;" colspan=2>
<input id="content"/>
</td>
</tr>
<tr>
<td style="width:100%;" colspan=2>
<canvas id="myCanvas" height="6">
Your browser does not support the canvas element.
</canvas>
</td>
</tr>
</table>
<audio id='music'>
<source src="music/Windows XP 启动.wav" type="audio/mpeg">
Your browser does not support the audio tag.
</audio>
<audio id='music2'>
<source src="music/Windows XP 关机.wav" type="audio/mpeg">
Your browser does not support the audio tag.
</audio>
<script type="text/javascript" >
var timer = {
initMinutes:30,
restSeconds:0,
minute:0,
second:0,
handle:0,
stopFlag:false,
startTime:0,
content:"asdasd",
coverFlag:false,
setFontSize:function(){
document.getElementById("numbers").style.fontSize = (window.innerWidth
|| document.documentElement.clientWidth
|| document.body.clientWidth) / 3 + "px"
},
refreshTable:function(){
//进度条
var table = document.getElementById("table1")
var span = document.getElementById('numbers')
//刷新进度条
//table2.style.width =
table.style.width = span.offsetWidth + "px"
var progress = 1
if(this.restSeconds > 0)
progress = this.restSeconds / (this.initMinutes * 60)
document.querySelector('#table1 td:nth-of-type(1)').style.width = progress * 100 + "%"
var td2 = document.querySelector('#table1 td:nth-of-type(2)')
if (progress < 1){
td2.style.width = (1 - progress) * 100 + "%"
}else{
td2.style.display = "none"
}
var canvas = document.getElementById('myCanvas')
canvas.width = span.offsetWidth
var ctx = canvas.getContext("2d")
var rectWeight = progress * span.offsetWidth
ctx.clearRect(0, 0, span.offsetWidth, 20)
ctx.fillStyle = "#FF0000"
//console.log("rectWeight: " + rectWeight)
//console.log(progress * span.offsetWidth)
ctx.fillRect(0, 0, rectWeight, 20)
},
init:function(){
this.startTime = Date.now()
var span = document.getElementById('numbers')
this.setFontSize()
this.restSeconds = this.initMinutes * 60
this.minute = this.initMinutes
var obj = this
this.handle = setInterval(function(){
if(obj.stopFlag)
return
if(obj.restSeconds > 0){
span.innerHTML = "" + (obj.minute < 10 ? "0" + obj.minute : obj.minute) + ":" +
(!obj.coverFlag ? (obj.second < 10 ? "0" + obj.second : obj.second) : " ".repeat(4))
if(obj.restSeconds > 0){
obj.restSeconds -= 1
}
obj.minute = Math.floor(obj.restSeconds / 60)
obj.second = obj.restSeconds - obj.minute * 60
//刷新进度条
obj.refreshTable()
}else{
span.innerHTML = "Time "
window.clearInterval(obj.handle)
document.getElementById("music2").play()
//跑完后记录
var content = document.getElementById("content").value
obj.markdownRecord(content)
//不停地闪烁
window.setInterval(function(){
span.innerHTML = (span.innerHTML == "Time ")?"is up.":"Time "
}, 5000)
}
}, 1000)
document.getElementById("music").play()
var numbers = document.getElementById("numbers")
numbers.addEventListener("click", function(){
obj.coverFlag = !obj.coverFlag
})
numbers.addEventListener("dblclick", function(){
obj.stopFlag = !obj.stopFlag
})
document.getElementById('content').addEventListener("blur", function(){
if(obj.restSeconds > 0)
return
var content = document.getElementById("content").value
if(this.content != content){
this.content = content
obj.markdownRecord(content)
}
})
document.getElementById('table1').addEventListener("dblclick", function(){
console.log("timerHistory:")
console.log(localStorage.getItem('timerHistory'))
console.log("\n")
obj.exportHistory()
})
},
markdownRecord:function(content){
var records = []
var timerHistory = localStorage.getItem("timerHistory")
if(timerHistory != null){
records = JSON.parse(timerHistory)
}
var lastRecord = records[0]
if(lastRecord && lastRecord.start == this.startTime){
lastRecord.note = content
}else{
var history = {
start:this.startTime,
duration:this.initMinutes,
note:content
}
records.unshift(history)//数组头插入元素
}
var recordsJson = JSON.stringify(records)
//将结果存入本地
localStorage.setItem("timerHistory", recordsJson)
console.log(records[0])
console.log("Marked it Down.")
},
exportHistory:function(){
var filename = 'record' + Date.now() +'.txt'
var text = localStorage.getItem('timerHistory')
this.exportFile(filename, text)
},
exportFile:function(filename, text){
var element = document.createElement('a');
element.setAttribute('href', 'data:text/plain;charset=utf-8,' + encodeURIComponent(text));
element.setAttribute('download', filename);
element.style.display = 'none';
document.body.appendChild(element);
element.click();
document.body.removeChild(element);
}
}
window.onresize = function(){
timer.setFontSize()
timer.refreshTable()
}
//pause
window.onclick = function(){
//timer.stopFlag = !timer.stopFlag
}
//main
window.onload = function(){
timer.init()
}
</script>
</body>
</html>
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