JQUERY MOBILE: PROBLEM SUBMIT FORM

JQUERY MOBILE: PROBLEM SUBMIT FORM

Hello
I use this script to send the form data after validating it.
The problem is that when I press the send button it tells me that you have to complete the field (required) but still sends me the data to the server.
How can I change the code to send me the data only after the validation has been completed?


<!DOCTYPE html>

<html>
    <head>
        <title>Forms</title>
        <meta name="viewport" content="user-scalable=no, initial-scale=1, maximum-scale=1, minimum-scale=1, width=device-width">
        <link rel="stylesheet" href=" http://code.jquery.com/mobile/1.4.5/jquery.mobile-1.4.5.min.css" />

<script>
function sendMsg(){
$("#contatti").serialize()).done(function(data){
if(data){
alert("Messaggio inviato correttamente");
}else{
alert("Errore durante l'invio");
}
});
}
</script>
  <!--/*{nome:$("#nome").val(),  email:$("#email").val(), messaggio:$("#messaggio").val()*/-->
</head>
    <body>
       <div data-role="page" id="info-page">
    <div data-role="header" data-theme="b">
         <h1> Information</h1>

    </div>
    <div data-role="content">
    <form id="contatti" >
<div data-role="fieldcontain">
<label for="nome">Nome:</label>
<input name="nome" type="text" required="required" placeholder="Inserisci il tuo nome">
</div>
<div data-role="fieldcontain">
<label for="email">Email:</label>
<input name="email" type="email" required="required" placeholder="Inserisci la tua email">
</div>
<div data-role="fieldcontain">
<label for="messaggio">Messaggio:</label>
<textarea name="messaggio" rows="30" required="required" placeholder="Inserisci il messaggio"></textarea>
</div>
<input type="reset" value="reset" data-inline="true">
<input type="submit" value="invia" data-inline="true" onClick="sendMsg()">
</form>
    </div>
  <div data-role="footer" data-position="fixed">2018</div>
</div>    
        <script type="text/javascript" src="cordova.js"></script>
        <script type="text/javascript" src="js/index.js"></script>
    </body>
</html>