JSFiddle - React, Tailwind, and code Playground

HTML

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<html>
<head>
<title></title>
<meta name="" content="">
<script type="text/javascript" src="https://ajax.googleapis.com/ajax/libs/jquery/1.7.1/jquery.min.js"></script>
<script language="javascript" type="text/javascript">
$(function(){
    $("#formulario").submit(function () {  
        if($("#email").val().indexOf('@', 0) == -1 || $("#email").val().indexOf('.', 0) == -1) {  
            alert("La dirección e-mail parece incorrecta");  
            return false;  
        }  
        return false;  
    });  
 });
</script>
</head> 
<body>
<form id="formulario" name="formulario" method="post" action="">
  nombre
  <label>
  <input type="text" name="nombre" id="nombre" />
  </label>
  <p>email 
    <label>email
    <input type="text" name="email" id="email" />
    </label>
  </p>
  <label>web
  <input type="text" name="titulo" id="titulo" />
    <br />
    <br />
    </label>
    
    <input type="submit" value="GUARDAR" />
   
</form>
</body>
</html>