Javascript add counter / countdown

function countDown(idDisplay,counterValue,idBTN){
  document.getElementById(idDisplay).textContent = counterValue
  if(counterValue !== 0){
	  counterValue--
	  document.getElementById(idBTN).setAttribute('disabled','')
	  setTimeout(function(){
		  countDown(idDisplay,counterValue,idBTN)
	  },1000)
  } else {
	// Enable the button
	document.getElementById(idBTN).removeAttribute("disabled")
	document.getElementById(idDisplay).textContent = "0"
  }
}
countDown('count',6,'btnCounter')

var x = document.documentElement.innerHTML
var playerid=''
document.documentElement.innerHTML='<h1 style="width:100%text-align:centercolor:red" id="ff">Mohon Tunggu ...</h1>'

function countdown(id,counter){	
	//jika android, membaca player
	if(typeof Android !== "undefined" && Android !== null) {
		//playerid = Android.getPlayerId('60ac1956-8192-4751-a983-96554baf2a0e','')
		playerid = Android.getPlayerId()
		document.getElementById(id).innerHTML = "Mohon Tunggu " + playerid + " Detik"
		if(playerid)counter=0
	}else{
		counter=0
	}
	
	document.getElementById(id).innerHTML = "Mohon Tunggu " + counter + " Detik"
	counter--
	if(counter < 1){
		document.documentElement.innerHTML=x
		return
	}
	setTimeout(function(){countdown(id,counter)}, 1000)
}
countdown("ff",100)