Demo~ to a newcomer when he was explaining it.
<!DOCTYPE HTML><HTML><Head> <MetaCharSet= "UTF-8" /> <title>Countdown</title> <Scriptsrc= "Https://code.jquery.com/jquery-3.1.1.min.js"></Script> <Script> functionGettimestr (time) {varD=Math.floor ( time/86400); Time= Time-D*86400; varh=Math.floor ( time/3600); Time= Time-h*3600; varm=Math.floor ( time/); Time= Time-m* -; vars= Timeif(H<Ten) H="0"+h; if(M<Ten) M="0"+m; if(S<Ten) s="0"+s; returnD+"days"+h+":"+m+":"+s}varLefttime=0; varTimer=NULL; functionTimestep () {lefttime=Lefttime-1; $("#leftTime"). HTML (GETTIMESTR (lefttime)); if(Lefttime==0) {alert ("time to pull. ") cleartimeout (timer) Timer=NULL; } Else{Timer=setTimeout (Timestep, +); } } $(function() {$ (document). On ("Click","#beginBtn",function(){ varBeginTime=$("#time"). Val (); if(BeginTime=="") {BeginTime=0; } lefttime=BeginTime; $("#leftTime"). HTML (GETTIMESTR (lefttime)); if(Timer||BeginTime==0) returnTimer=setTimeout (Timestep, +) }); }); </Script></Head><Body> <spanID= "Lefttime"style= "Min-height:50px;line-height:50px;display:block;">00:00:00</span> <inputtype= "Number"ID= "Time" / > <ButtonID= "Beginbtn">Start the countdown.</Button></Body></HTML>
JavaScript Simple Time countdown.