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Client Side Validation with JavaScript in ASP.NET

By Puran Kaushal on Mar 22 2006
This simple program will guide how to do client side validation in JavaScript.
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This simple program will guide how to do client side validation of Form in JavaScript.

In this just make a form as follows:

  1. Name : <asp:TextBox ID="txtName" />
  2. Email : <asp:TextBox ID="txtEmail" />
  3. Web URL : <asp:TextBox ID="txtWebUrl" />
  4. Zip : <asp:TextBox ID="txtZip" />
  5. <asp:Button ID="btnSubmit" OnClientClick=" return validate()" runat="server" Text="Submit" />

Now on the source code of this form in script tag write the following code:

<script language="javascript" type="text/javascript">
function
validate()
{
      if (document.getElementById("<%=txtName.ClientID%>").value==""
)
      {
                 alert("Name Feild can not be blank"
);
                 document.getElementById(
"<%=txtName.ClientID%>"
).focus();
                 return false
;
      }
      if(document.getElementById("<%=txtEmail.ClientID %>").value==""
)
      {
                 alert(
"Email id can not be blank"
);
                document.getElementById("<%=txtEmail.ClientID %>"
).focus();
                return false
;
      }
     var
emailPat = /^(\".*\"|[A-Za-z]\w*)@(\[\d{1,3}(\.\d{1,3}){3}]|[A-Za-z]\w*(\.[A-Za-z]\w*)+)$/;
     var emailid=document.getElementById("<%=txtEmail.ClientID %>"
).value;
     var
matchArray = emailid.match(emailPat);
     if (matchArray == null
)
    {
               alert(
"Your email address seems incorrect. Please try again."
);
               document.getElementById(
"<%=txtEmail.ClientID %>"
).focus();
               return false
;
    }
    if(document.getElementById("<%=txtWebURL.ClientID %>").value==""
)
    {
               alert(
"Web URL can not be blank"
);
               document.getElementById(
"<%=txtWebURL.ClientID %>").value=
"http://"
               document.getElementById("<%=txtWebURL.ClientID %>"
).focus();
               return false
;
    }
    var Url=
"^[A-Za-z]+://[A-Za-z0-9-_]+\\.[A-Za-z0-9-_%&\?\/.=]+$"
    var tempURL=document.getElementById("<%=txtWebURL.ClientID%>"
).value;
    var
matchURL=tempURL.match(Url);
     if(matchURL==null
)
     {
               alert(
"Web URL does not look valid"
);
               document.getElementById(
"<%=txtWebURL.ClientID %>"
).focus();
               return false
;
     }
     if (document.getElementById("<%=txtZIP.ClientID%>").value==""
)
     {
               alert(
"Zip Code is not valid"
);
               document.getElementById(
"<%=txtZIP.ClientID%>"
).focus();
               return false
;
     }
     var digits="0123456789"
;
     var
temp;
     for (var i=0;i<document.getElementById("<%=txtZIP.ClientID %>"
).value.length;i++)
     {
               temp=document.getElementById(
"<%=txtZIP.ClientID%>"
).value.substring(i,i+1);
               if
(digits.indexOf(temp)==-1)
               {
                        alert(
"Please enter correct zip code"
);
                        document.getElementById(
"<%=txtZIP.ClientID%>"
).focus();
                        return false
;
               }
     }
     return true
;
}
</script>

And in code behind file just write the below code.

Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
               btnSubmit.Attributes.Add(
"onclick", "return validate()"
)
End Sub

Now you will get a form with proper validation.

I hope this is going to help you.