Date Validation in JavaScript

Introduction

This code is developed to validate date entered in a web page. I found several other code snippets that provide a solution, but they are all vague and confusing, while this JavaScript script provides an easy method of validating a date. Check out this.

Using the code

Shown below is the core code for the date validation, written in JavaScript:

//
 function IsValidDate(Day,Mn,Yr){
    var DateVal = Mn + "/" + Day + "/" + Yr;
    var dt = new Date(DateVal);

    if(dt.getDate()!=Day){
        alert('Invalid Date');
        return(false);
        }
    else if(dt.getMonth()!=Mn-1){
    //this is for the purpose JavaScript starts the month from 0
        alert('Invalid Date');
        return(false);
        }
    else if(dt.getFullYear()!=Yr){
        alert('Invalid Date');
        return(false);
        }
        
    return(true);
 }
//

If you plan to add this to a custom validator in ASP.NET, then the following method will do:

The code below is written for calling the above JavaScript function:

function CallDateFun(sender, args){
   var d=document.getElementById("DayDropDownListCtl").value
   var m=document.getElementById("MonthDropDownListCtl").value
   var y=document.getElementById("YearDropDownListCtl").value

   if(IsValidDate(d,m,y))
        args.IsValid=true;
   else
        args.IsValid=false;
}

This is the code for the custom validator:

<asp:CustomValidator ID="CustomDateValidatorCtl" 
  runat="server"  ClientValidationFunction="CallDateFun" 
  Text="Invalid Date" ControlToValidate="DayDropDownListCtl">
</asp:CustomValidator>

Note: DayDropDownListCtl, MonthDropDownListCtl, and YearDropDownListCtl are the dropdown lists for the date, month, and year, respectively.