动态脚本倒计时脚本，让你计数到相对事件以后的一个日期/时间。比如到某个节日的声誉时间，如圣诞节，你妈妈的生日， 2015年4月1日等 。此脚本是非常灵活的，通过自定义格式功能，您可以自定义究竟如何显示输出，或时间到了以后执行一个特定的事件（如：转向另外一个网页） 。
第一步：
在网页<head>区添加以下代码
<style style="text/css">
.lcdstyle{ /*Example CSS to create LCD countdown look*/
background-color:black;
color:yellow;
font: bold 18px MS Sans Serif;
padding: 3px;
}
.lcdstyle sup{ /*Example CSS to create LCD countdown look*/
font-size: 80%
}
</style>
<script type="text/javascript">
/*****************************************************
* Share JavaScript (http://www.ShareJS.com)
* 使用此脚本程序，请保留此声明
* 获取此脚本以及更多的JavaScript程序，请访问 http://www.ShareJS.com
******************************************************/
function cdtime(container, targetdate){
if (!document.getElementById || !document.getElementById(container)) return
this.container=document.getElementById(container)
this.currentTime=new Date()
this.targetdate=new Date(targetdate)
this.timesup=false
this.updateTime()
}
cdtime.prototype.updateTime=function(){
var thisobj=this
this.currentTime.setSeconds(this.currentTime.getSeconds()+1)
setTimeout(function(){thisobj.updateTime()}, 1000) //update time every second
}
cdtime.prototype.displaycountdown=function(baseunit, functionref){
this.baseunit=baseunit
this.formatresults=functionref
this.showresults()
}
cdtime.prototype.showresults=function(){
var thisobj=this
var timediff=(this.targetdate-this.currentTime)/1000 //difference btw target date and current date, in seconds
if (timediff<0){ //if time is up
this.timesup=true
this.container.innerHTML=this.formatresults()
return
}
var oneMinute=60 //minute unit in seconds
var oneHour=60*60 //hour unit in seconds
var oneDay=60*60*24 //day unit in seconds
var dayfield=Math.floor(timediff/oneDay)
var hourfield=Math.floor((timediff-dayfield*oneDay)/oneHour)
var minutefield=Math.floor((timediff-dayfield*oneDay-hourfield*oneHour)/oneMinute)
var secondfield=Math.floor((timediff-dayfield*oneDay-hourfield*oneHour-minutefield*oneMinute))
if (this.baseunit=="hours"){ //if base unit is hours, set "hourfield" to be topmost level
hourfield=dayfield*24+hourfield
dayfield="n/a"
}
else if (this.baseunit=="minutes"){ //if base unit is minutes, set "minutefield" to be topmost level
minutefield=dayfield*24*60+hourfield*60+minutefield
dayfield=hourfield="n/a"
}
else if (this.baseunit=="seconds"){ //if base unit is seconds, set "secondfield" to be topmost level
var secondfield=timediff
dayfield=hourfield=minutefield="n/a"
}
this.container.innerHTML=this.formatresults(dayfield, hourfield, minutefield, secondfield)
setTimeout(function(){thisobj.showresults()}, 1000) //update results every second
}
/////CUSTOM FORMAT OUTPUT FUNCTIONS BELOW//////////////////////////////
//Create your own custom format function to pass into cdtime.displaycountdown()
//Use arguments[0] to access "Days" left
//Use arguments[1] to access "Hours" left
//Use arguments[2] to access "Minutes" left
//Use arguments[3] to access "Seconds" left
//The values of these arguments may change depending on the "baseunit" parameter of cdtime.displaycountdown()
//For example, if "baseunit" is set to "hours", arguments[0] becomes meaningless and contains "n/a"
//For example, if "baseunit" is set to "minutes", arguments[0] and arguments[1] become meaningless etc
function formatresults(){
if (this.timesup==false){//if target date/time not yet met
var displaystring=arguments[0]+" days "+arguments[1]+" hours "+arguments[2]+" minutes "+arguments[3]+" seconds left until March 23, 2009 18:25:00"
}
else{ //else if target date/time met
var displaystring="Future date is here!"
}
return displaystring
}
function formatresults2(){
if (this.timesup==false){ //if target date/time not yet met
var displaystring="<span class='lcdstyle'>"+arguments[0]+" <sup>days</sup> "+arguments[1]+" <sup>hours</sup> "+arguments[2]+" <sup>minutes</sup> "+arguments[3]+" <sup>seconds</sup></span> left until this Christmas"
}
else{ //else if target date/time met
var displaystring="" //Don't display any text
alert("Christmas is here!") //Instead, perform a custom alert
}
return displaystring
}
</script>
第二步：
在<body>区希望显示倒计时信息的地方添加以下脚本
<div id="countdowncontainer"></div>
<br />
<div id="countdowncontainer2"></div>
<script type="text/javascript">
var futuredate=new cdtime("countdowncontainer", "March 23, 2009 18:25:00")
futuredate.displaycountdown("days", formatresults)
var currentyear=new Date().getFullYear()
//dynamically get this Christmas' year value. If Christmas already passed, then year=current year+1
var thischristmasyear=(new Date().getMonth()>=11 && new Date().getDate()>25)? currentyear+1 : currentyear
var christmas=new cdtime("countdowncontainer2", "December 25, "+thischristmasyear+" 0:0:00")
christmas.displaycountdown("days", formatresults2)
</script>
第二步显示了如何在网页上通过调用cdtime()函数显示倒计时信息
new cdtime("ID_of_DIV_container", "target_date")
ID_of_DIV_container (string): 用于显示倒计时文本
target_date (string): 结束日期字符串, 格式如下: "March 23, 2009 18:25:00". 使用24小时格式.
要显示具体的信息需要调用 cdtime().displaycountdown(). 下面详细解释了这个函数的用法:
cdtime.displaycountdown("base_unit", formatfunction_reference)
base_unit (string): 倒计时的最小单位，它的值可以是"days","hours","minutes" 或者"seconds"。比如你选择了"hours"，倒计时的最小单位就是小时，每隔1小时倒计时会跳动一下
formatfunction_reference (string): 一个自定义个的函数，你可以在这个函数里定义倒计时显示的格式，或者事件（如：倒计时结束时转向另外一个网页）。
下面有一个定义好的函数，大家可以参考
/////CUSTOM FORMAT OUTPUT FUNCTIONS BELOW//////////////////////////////
//Create your own custom format function to pass into cdtime.displaycountdown()
//Use arguments[0] to access "Days" left
//Use arguments[1] to access "Hours" left
//Use arguments[2] to access "Minutes" left
//Use arguments[3] to access "Seconds" left
//The values of these arguments may change depending on the "baseunit" parameter of cdtime.displaycountdown()
//For example, if "baseunit" is set to "hours", arguments[0] becomes meaningless and contains "n/a"
//For example, if "baseunit" is set to "minutes", arguments[0] and arguments[1] become meaningless etc
function formatresults2(){
if (this.timesup==false){ //if target date/time not yet met
var displaystring="<span class='lcdstyle'>"+arguments[0]+" <sup>days</sup> "+arguments[1]+" <sup>hours</sup> "+arguments[2]+" <sup>minutes</sup> "+arguments[3]+" <sup>seconds</sup></span> left until this Christmas"
}
else{ //else if target date/time met
var displaystring="" //Don't display any text
alert("Christmas is here!") //Instead, perform a custom alert
}
return displaystring
}
