Validate TextBox using JavaScript

In this blog we will know how to Validate Textbox using javascript.

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="WebForm1.aspx.cs" Inherits="Validate_Textbox_using_javascript.WebForm1" %>
<!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">
    <title>Untitled Page</title>
    <script language="javascript" type="text/javascript">
        function validate()
        {
           if (document.getElementById("<%=txt_name.ClientID%>").value=="")
           {
                 alert("Name Feild can not be blank");
                 document.getElementById("<%=txt_name.ClientID%>").focus();
                 return false;
           }
           return true;
        }
    </script>
</head>
<body>
    <form id="form1" runat="server">
    <div>
        <asp:TextBox ID="txt_name" runat="server"></asp:TextBox>
    <asp:Button ID="btn_register" runat="server"  OnClientClick ="javascript:validate()"                        Text="Register" onclick="btn_register_Click"/>
        <asp:Label ID="lblmsg" runat="server" Text="Label"></asp:Label>
    </div>
    </form>
</body>
</html> 

using System;
using System.Collections;
using System.Configuration;
using System.Data;
using System.Linq;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Xml.Linq;
using System.Data.SqlClient;
namespace Validate_Textbox_using_javascript
{
    public partial class WebForm1 : System.Web.UI.Page
    {
        string connStr = ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString;
        SqlCommand com;
        protected void btn_register_Click(object sender, EventArgs e)
        {
            if (txt_name.Text == "")
            {
                txt_name.Focus();
            }
            else
            {
                SqlConnection con = new SqlConnection(connStr);
                com = new SqlCommand();
                com.Connection = con;
                com.CommandType = CommandType.Text;
                com.CommandText = "insert into test values(@name)";
                com.Parameters.Clear();
                com.Parameters.AddWithValue("@name", txt_name.Text);
                if (con.State == ConnectionState.Closed)
                    con.Open();
                com.ExecuteNonQuery();
                con.Close();
                lblmsg.Text = "Data entered successfully!!!";
            }
        }
    }
}

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