date validations with javascript

Question

I need sample javascript code to validate the date with mm-dd-yyyy format.

1) if user enters wrong date with respect to above date format.

2) Date range validations,start date and end date range validations.

Any help on this appreciated.

Regards, Chaitu

Answer 1

Validating the format could be something like:

function isValidDateFormat(s) {
  return /^\d\d-\d\d-\d\d\d\d$/.test(s);
}

For date ranges, convert the string to a date object and compare it to date objects for the limits of the range.

Here's a date validation function - no need to check the format of the input, if it's wrong, the function returns false:

// Expects date in US-specific mm-dd-yyyy or 
// mm/dd/yyyy format
function isValidDate(d) {
  var bits = d.split(/[-/]/);
  var date = new Date(bits[2] + '/'
                    + bits[0] + '/'
                    + bits[1]);
  return date && (date.getMonth()+1) == bits[0]
              && date.getDate() == bits[1]; 
}

So now you have how to validate the format, how to validate a date and how to convert a string to a date object. Should be pretty simple to do the comparison from here.

Answer 2

A detailed one, I used years back...

<script language = "Javascript">
  var dtCh= "/";
  var minYear=1900;
  var maxYear=2100;

  var isInteger = function(s){
    var i;
      for (i = 0; i < s.length; i++){   
          var c = s.charAt(i);
          if (((c < "0") || (c > "9"))) return false;
      }      
      return true;
  }

  var stripCharsInBag = function(s, bag){
    var i;
      var returnString = "";
      for (i = 0; i < s.length; i++){   
          var c = s.charAt(i);
          if (bag.indexOf(c) == -1) returnString += c;
      }
      return returnString;
  }

  var daysInFebruary = function(year){
      return (((year % 4 == 0) && ( (!(year % 100 == 0)) || (year % 400 == 0))) ? 29 : 28 );
  }

  var DaysArray = function(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
  }

  var isDate = function(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){
        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 (strYear.length != 4 || year==0 || year<minYear || year>maxYear){
        alert("Please enter a valid 4 digit year between "+minYear+" and "+maxYear)
        return false
    }
    if (dtStr.indexOf(dtCh,pos2+1)!=-1 || isInteger(stripCharsInBag(dtStr, dtCh))==false){
        alert("Please enter a valid date")
        return false
    }
  return true
  }

  var ValidateForm = function(){
    var dt=document.frmSample.txtDate
    if (isDate(dt.value)==false){
        dt.focus()
        return false
    }
      return true
   }

</script>

And a bit of html for demonstration:

<form method="get" onSubmit="return ValidateForm()">
  <p>Enter a Date <b>(mm/dd/yyyy)</b>: <input type="text" name="txtDate" maxlength="10" size="15"></p>
  <p><input type="submit" value="Submit"></p>
</form>