Javascript Validation in ASP.net

in this web programming tutorial we will learn that how we can validate asp.net form fields using javascript. See the below function and use it as per your requirements.

function validateregform()
{

if (document.getElementById("<%=txtName.ClientID%>").value=="")
{
alert("Name Field 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<%=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;
}