function addRow()
{
  var tbl = document.getElementById('applications');
  var lastRow = tbl.rows.length;
  // if there's no header row in the table, then iteration = lastRow + 1
  var iteration = lastRow;
  var row = tbl.insertRow(lastRow);

  
  // right cell
  var cellRight = row.insertCell(0);
  var el = document.createElement('input');

  el.type = 'text';
  el.name = 'application_n' + iteration;
  el.id = 'application_n' + iteration;
  el.size = 45;
  el.className='cellData';
  el.style.width='220px'
  el.style.height='17px'
  cellRight.appendChild(el);
 
  alert("the id is " + el.id)
  
  
  
  
  
  var cellMiddle = row.insertCell(1);
  var fl = document.createElement('input');

  fl.type = 'text';
  fl.name = 'application_no' + iteration;
  fl.id = 'application_no' + iteration;
  fl.size = 45;
  fl.className='cellData';
  fl.style.width='220px'
  fl.style.height='17px'
  cellMiddle.appendChild(fl);
  
  
  var cellLeft = row.insertCell(2);
  var gl = document.createElement('input');

  gl.type = 'text';
  gl.name = 'application_doj' + iteration;
  gl.id = 'application_doj' + iteration;
  gl.size = 45;
  gl.className='cellData';
  gl.style.width='220px'
  gl.style.height='17px'
  gl.value='mm/dd/yyyy'
  gl.onfocus= function() {gl.value=""};
  gl.onblur= function() {ValidateForm()};
  cellLeft.appendChild(gl);
  document.getElementById("no_of_applications").value=iteration
   
  }

 
var dtCh= "/";
var minYear=1900;
var maxYear=2100;
 
function isInteger(s){
	var i;
    for (i = 0; i < s.length; i++){   
        // Check that current character is number.
        var c = s.charAt(i);
        if (((c < "0") || (c > "9"))) return false;
    }
    // All characters are numbers.
    return true;
}
 
function stripCharsInBag(s, bag){
	var i;
    var returnString = "";
    // Search through string's characters one by one.
    // If character is not in bag, append to returnString.
    for (i = 0; i < s.length; i++){   
        var c = s.charAt(i);
        if (bag.indexOf(c) == -1) returnString += c;
    }
    return returnString;
}
 
function daysInFebruary (year){
	// February has 29 days in any year evenly divisible by four,
    // EXCEPT for centurial years which are not also divisible by 400.
    return (((year % 4 == 0) && ( (!(year % 100 == 0)) || (year % 400 == 0))) ? 29 : 28 );
}
function DaysArray(n) {
	for (var i = 1; i <= n; i++) {
		this[i] = 31
		if (i==4 || i==6 || i==9 || i==11) {this[i] = 30}
		if (i==2) {this[i] = 29}
   } 
   return this
}
 
function isDate(dtStr){
	var daysInMonth = DaysArray(12)
	var pos1=dtStr.indexOf(dtCh)
	var pos2=dtStr.indexOf(dtCh,pos1+1)
	var strMonth=dtStr.substring(0,pos1)
	var strDay=dtStr.substring(pos1+1,pos2)
	var strYear=dtStr.substring(pos2+1)
	strYr=strYear
	if (strDay.charAt(0)=="0" && strDay.length>1) strDay=strDay.substring(1)
	if (strMonth.charAt(0)=="0" && strMonth.length>1) strMonth=strMonth.substring(1)
	for (var i = 1; i <= 3; i++) {
		if (strYr.charAt(0)=="0" && strYr.length>1) strYr=strYr.substring(1)
	}
	month=parseInt(strMonth)
	day=parseInt(strDay)
	year=parseInt(strYr)
	if (pos1==-1 || pos2==-1){
		document.getElementById("DOJ_error").innerHTML = "please enter a date in - mm/dd/yyyy format"
		return false
	}
	if (strMonth.length<1 || month<1 || month>12){
		document.getElementById("DOJ_error").innerHTML = "Please enter a valid month"
 
		return false
	}
	if (strDay.length<1 || day<1 || day>31 || (month==2 && day>daysInFebruary(year)) || day > daysInMonth[month]){
		document.getElementById("DOJ_error").innerHTML = "Please enter a valid day"
		return false
	}
	if (strYear.length != 4 || year==0 || year<minYear || year>maxYear){
		document.getElementById("DOJ_error").innerHTML = "Please enter a valid 4 digit year"
 
		return false
	}
	if (dtStr.indexOf(dtCh,pos2+1)!=-1 || isInteger(stripCharsInBag(dtStr, dtCh))==false){
		document.getElementById("DOJ_error").innerHTML = "Please enter a valid date"
 
		return false
	}
return true
}
function ValidateForm()
	{
	alert("hi from ValidateForm")
	//var dt=document.transaction.application_doj' + iteration
	//alert(dt)
	iteration=document.getElementById("no_of_applications").value
	alert(iteration)
  	 var dt=document.getElementById("application_doj" + iteration).value
   	// var dt=document.getElementById("application_doj2").value	
 
	alert(dt)
	if (isDate(dt.value)==false){
		//dt.focus()
		return false
	}
	else
	{
	document.getElementById("DOJ_error").innerHTML=""
    return true
    }
 }

<span id="DOJ_error"></span>