<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="WebForm1.aspx.cs" Inherits="WebApplication1.WebForm1" %>
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title></title>
<script>
//Way 1
function Validate1() {
var a = document.getElementById("TextBox1").value;
var b = a.split(' ');
var c = 0;
for (var i = 0; i < b.length; i++) {
if (b[i] == '') {
c++;
if (c == 2) {
document.getElementById("TextBox1").value = a.substring(0, a.length - 1);
return false;
}
}
}
}
//Way 2
function Validate2() {
var a = document.getElementById("TextBox2").value;
var b = a.split(' ');
var c = 0;
for (var i = 0; i < b.length; i++) {
if (b[i] == '') {
c++;
if (c == 2) {
alert('Only one space allowed in/between the word.');
document.getElementById("TextBox2").value = a.substring(0, a.length - 1);
return false;
}
}
}
}
</script>
</head>
<body>
<form id="form1" runat="server">
<div>
Way 1 (Without Message) :-<asp:TextBox ID="TextBox1" runat="server" onkeyup="Validate1();" ClientIDMode="Static"></asp:TextBox>
<br />
<br />
Way 2 (Alert With Message) :-<asp:TextBox ID="TextBox2" runat="server" onkeyup="Validate2();" ClientIDMode="Static"></asp:TextBox>
</div>
</form>
</body>
</html>
