How to validate asp.net form using Jquery

In this post I will show you how to validate asp.net form using jqery. Create a new website,add a new js file ,and add following code inside it
function validateForm(e) {
    var formIsValid = true;
    // check that a valid email address has been entered
    var emailRegExp = /[A-Z0-9._%+-]+@[A-Z0-9.-]+\.[A-Z]{2,4}/;
    if (!emailRegExp.test(String($("#txtEmail").val()).toUpperCase())) {
        addError("txtEmail", "Please enter a valid email address.");
        formIsValid = false;
    } else {
        removeError("txtEmail");
    }

    // check that first name has one or more characters
    if ($("#txtFirstName").val() == '') {
        addError("txtFirstName", "This field is required.");
        formIsValid = false;
    } else {
        removeError("txtFirstName");
    }
    // check that last name has one or more characters
    if ($("#txtLastName").val() == '') {
        addError("txtLastName", "This field is required.");
        formIsValid = false;
    } else {
        removeError("txtLastName");
    }

    // check that a valid phone number is entered
    var phoneRegExp = /^\(?[1-9]\d{2}\)?\s?\-?\.?\d{3}\s?\-?\.?\d{4}$/;
    if (!phoneRegExp.test($("#txtPhone").val())) {
        addError("txtPhone", "Valid phone number required.");
        formIsValid = false;
    } else {
        removeError("txtPhone");
    }

    if (!formIsValid) {
        e.preventDefault();
    }
}

function addError(id, msg) {
    if ($("#" + id).parent().find("label[class=error]").attr("generated") == "true") {
        $("#" + id).parent().find("label[class=error]").css("display", "block");
    } else {
        $("#" + id).parent().append('<label for="' + id + '" generated="true" class="error">' + msg + '</label>').css("display", "block");
    }
}
function removeError(id) {
    $("#" + id).parent().find("label[class=error]").css("display", "none");
}
Add a new page.Then add reference of jquery and above js file
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default2.aspx.cs" Inherits="Default2" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <script type="text/javascript" src="Scripts/jquery-1.4.1.js"></script>
    <script type="text/javascript" src="Scripts/Validation.js"></script>
    <title></title>
    <script type="text/javascript">
        $(document).ready(function () {
            $(".submitForm").click(function (e) {
                validateForm(e);
            });
        });
    </script>
    <style type="text/css">
    .error{color:Red;}
    </style>
</head>
<body>
    <form id="form1" runat="server">
    <table class="style1">
        <tr>
            <td>
                FirstName
            </td>
            <td>
                <asp:TextBox ID="txtFirstName"  runat="server"></asp:TextBox>
            </td>
        </tr>
        <tr>
            <td>
                LastName
            </td>
            <td>
                <asp:TextBox ID="txtLastName"  runat="server"></asp:TextBox>
            </td>
        </tr>
        <tr>
            <td>
                Phone Number
            </td>
            <td>
                <asp:TextBox ID="txtPhone"  runat="server"></asp:TextBox>
            </td>
        </tr>
        <tr>
            <td>
                Email
            </td>
            <td>
                <asp:TextBox ID="txtEmail"  runat="server"></asp:TextBox>
            </td>
        </tr>
    </table>
    <div>
        <input type="button" id="btnSubmit" class="submitForm" value="Submit" />
    </div>
    </form>
</body>
</html>