Asp.Net Client side Validation using Java Script

This simple program will guide how to do client side validation of Form in

In this just make a form as follows:

Name : <asp:TextBox ID="txtName" />

Email : <asp:TextBox ID="txtEmail" />

Web URL : <asp:TextBox ID="txtWebUrl" />

Zip : <asp:TextBox ID="txtZip" />

<asp:Button ID="btnSubmit" OnClientClick=" return validate()" runat="server" Text="Submit" />

Now on the sourcecode 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*)+)$/;
var emailid=document.getElementById("<%=txtEmail.ClientID %>").value;
var matchArray = emailid.match(emailPat);
if (matchArray == null)
{
alert("Your email seems incorrect. Please try again.");
document.getElementById("<%=txtEmail.ClientID %>").focus();
return false;
}
if(document.getElementById("<%=txtWebURL.ClientID %>").value=="")
{
alert("Web URL can not be blank");
document.getElementById("<%=txtWebURL.ClientID %>").value="http://"
document.getElementById("<%=txtWebURL.ClientID %>").focus();
return false;
}
var Url="^[A-Za-z]+://[A-Za-z0-9-_]+\\.[A-Za-z0-9-_%&\?\/.=]+$"
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"<%=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 void Page_Load(object sender, EventArgs e)
{
btnSubmit.Attributes.Add("onClick", " return validate()");


}