var dtCh= "/";
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 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 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++) {

    // Check that current character isn't whitespace.
    var c = s.charAt(i);
    if (bag.indexOf(c) == -1) returnString += c;

  }

  return returnString;

}


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(dtStr=="")
  {
  	return(true);
  }
  
  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) {

    alert("The date format should be : mm/dd/yyyy");
    return (false);

  }

  if (strMonth.length<1 || month<1 || month>12) {

    alert("Please enter a valid month.");
    return (false);

  }

  if (strDay.length<1 || day<1 || day>31 || (month==2 && day>daysInFebruary(year)) || day > daysInMonth[month]) {

    alert("Please enter a valid day.");
    return (false);

  }

  

  if (dtStr.indexOf(dtCh,pos2+1)!=-1 || isInteger(stripCharsInBag(dtStr, dtCh))==false) {

    alert("Please enter a valid date.");
    return (false);

  }

  return (true);

}