I have a javascript timer and here is the code
Code:
function cdtime(container, targetdate){
if (!document.getElementById || !document.getElementById(container)) return
this.container=document.getElementById(container)
this.currentTime=new Date("<?= strftime('%c') ?>")
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()
	document.broadCastForm.submit();
	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[1]+" hours "+arguments[2]+" minutes "+arguments[3]+" seconds left until show starts"
	} else{ //else if target date/time met
		var displaystring="Showtime";
	}
	return displaystring
}
What I need for it to do, is when it counts down to zero, I need for it to auto submit a form.

I have tried adding in document.formName.submit(); and it didn't work.

How can I get this to autosubmit when it counts down to zero?