Form validation

$(document).ready(function(){
 
	// hide messages 
	$("#error").hide();
	$("#success").hide();
 
	// on submit...
	$("#send").click(function() {
		$("#error").hide();
 
		//required:
 
		//name
		var name = $("input#name").val();
		if(name == ""){
			$("#error").fadeIn().text("Name required.");
			$("input#name").focus();
			return false;
		}
 
		// email
		var email = $("input#email").val();
		if(email == ""){
			$("#error").fadeIn().text("Email required");
			$("input#email").focus();
			return false;
		}
 
		// web
		var web = $("input#web").val();
		if(web == ""){
			$("#error").fadeIn().text("Web required");
			$("input#web").focus();
			return false;
		}
 
		// comments
		var comments = $("#comments").val();
 
		// data string
		var dataString = 'name='+ name
						+ '&email=' + email        
						+ '&web=' + web
						+ '&comments=' + comments;
 
		// ajax
		$.ajax({
			type:"POST",
			url: "send-mail.php",
			data: dataString,
			success: success()
		});
	});  
 
 
	// on success...
	 function success(){
	 	$("#success").fadeIn();
	 	$("#formMail").fadeOut();
	 }
 
    return false;
});
 
 
 
// usage
		<!-- form -->
		<form id="formMail" action="#" method="post">
			<fieldset>
				<p>
					<label>Name:</label>
					<input name="name"  id="name" type="text" />
				</p>
				<p>
					<label>Email:</label>
					<input name="email"  id="email" type="text" />
				</p>
				<p>
					<label>Web:</label>
					<input name="web"  id="web" type="text" />
				</p>
				<p>
					<label>Comments:</label>
					<textarea  name="comments"  id="comments" rows="5" cols="20" ></textarea>
				</p>
				<br/><br/>	
				<p><input type="button" value=" " name="send" id="send" /></p>
			</fieldset>
			<p id="error">Message</p>
		</form>
		<p id="success">Thanks for your comments.</p>
		<!-- ENDS form -->