js sample code to implement countdown clock_javascript skills

As shown below:

Copy the codeThe code is as follows:

if (document.all||document.getElementById)
document.write('< ;/span>')

window.onload=start_countdown

function countdown(){
var today=new Date()
var todayy=today.getYear()
if (todayy todayy =1900
var todaym=today.getMonth()
var todayd=today.getDate()
var todayh=today.getHours()
var todaymin=today.getMinutes()
var todaysec=today. getSeconds()
var todaystring=montharray[todaym] " " todayd ", " todayy " " todayh ":" todaymin ":" todaysec
futurestring=montharray[mo-1] " " da ", " yr
dd=Date.parse(futurestring)-Date.parse(todaystring)
dday=Math.floor(dd/(60*60*1000*24)*1)
dhour=Math.floor(( dd%(60*60*1000*24))/(60*60*1000)*1)
dmin=Math.floor(((dd%(60*60*1000*24))%(60* 60*1000))/(60*1000)*1)
dsec=Math.floor(((dd%(60*60*1000*24))%(60*60*1000))%(60 *1000))/1000*1)
if(ddayif (document.layers){
document.countdownnsmain.document .countdownnssub.document.write(opentags message_on_occasion closetags)
document.countdownnsmain.document.countdownnssub.document.close()
}
else if (document.all||document.getElementById)
crosscount .innerHTML=opentags message_on_occasion closetags
return
}
else if (ddayif (document.layers){
document.countdownnsmain.document.countdownnssub.document. write(opentags "Time has passed!" closetags)
document.countdownnsmain.document.countdownnssub.document.close()
}
else if (document.all||document.getElementById)
crosscount.innerHTML=opentags "Occasion already passed! " closetags
return
}
else{
if (document.layers){
document.countdownnsmain.document.countdownnssub.document.write( opentags dday " days, " dhour " hours, " dmin " minutes, and " dsec " seconds left until " occasion closetags)
document.countdownnsmain.document.countdownnssub.document.close()
}
else if (document.all||document.getElementById)
crosscount.innerHTML=opentags "and " dday " days, " dhour " hours, " dmin " minutes, " dsec " seconds are " occasion closetags
}
setTimeout("countdown()",1000)
}

height="&{countdownheight};" width="&{countdownwidth};">< ;LAYER
id=countdownnssub height="&{countdownheight};"
width="&{countdownwidth};" top="0" left="0">> ;