date_functions.js

function isValidDate(date)
{
    var matches = /^(\d{1,2})[-\/](\d{1,2})[-\/](\d{4})$/.exec(date);
    if (matches == null) return false;
    var d = matches[1];
    var m = matches[2] - 1;
    var y = matches[3];
    var composedDate = new Date(y, m, d);
    return composedDate.getDate() == d &&
            composedDate.getMonth() == m &&
            composedDate.getFullYear() == y;
}
//valid date including leap years
function isValidLeapDate(date) {
        var valid = true;

        date = date.replace('/-/g', '');

        var month = parseInt(date.substring(0, 2),10);
        var day   = parseInt(date.substring(2, 4),10);
        var year  = parseInt(date.substring(4, 8),10);

        if(isNaN(month) || isNaN(day) || isNaN(year)) return false;

        if((month < 1) || (month > 12)) valid = false;
        else if((day < 1) || (day > 31)) valid = false;
        else if(((month == 4) || (month == 6) || (month == 9) || (month == 11)) && (day > 30)) valid = false;
        else if((month == 2) && (((year % 400) == 0) || ((year % 4) == 0)) && ((year % 100) != 0) && (day > 29)) valid = false;
        else if((month == 2) && ((year % 100) == 0) && (day > 29)) valid = false;
        else if((month == 2) && (day > 28)) valid = false;

    return valid;
}
function isvalidRegEx(subject){
  if (subject.match(/^(?:(0[1-9]|[12][0-9]|3[01])[\- \/.](0[1-9]|1[012])[\- \/.](19|20)[0-9]{2})$/)){
    return true;
  }else{
    return false;
  }
}
function getjsDate(date)
	{
	var matches = /^(\d{1,2})[-\/](\d{1,2})[-\/](\d{4})$/.exec(date);
    if (matches == null) return false;
    var d = matches[1];
    var m = matches[2] - 1;
    var y = matches[3];
    var composedDate = new Date(y, m, d);
	return composedDate;
	}
	//http://www.htmlgoodies.com/html5/javascript/calculating-the-difference-between-two-dates-in-javascript.html
	function getdiffDate(date1, date2 )
	{
		
  //Get 1 day in milliseconds
  var one_day=1000*60*60*24;

  // Convert both dates to milliseconds
  var date1_ms = date1.getTime();
  var date2_ms = date2.getTime();

  // Calculate the difference in milliseconds
  var difference_ms = date2_ms - date1_ms;
    
  // Convert back to days and return
  return Math.round(difference_ms/one_day); 
		
	}
function increasedatebyDays(date,days)
{
  var temp = date;
temp.setTime( temp.getTime() + days * 86400000 );		
  return temp;
}