Buongiorno a tutti,
Ho un problema con la validazione dei dati e i messaggi passati all'utente.
Cliccando su submit non controlla i dati inseriti.






jQuery Validation Plugin v1.19.0
jQuery Mobile 1.4.5
jQuery JavaScript Library v1.12.4

<html>
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<link rel="stylesheet" type="text/css" href="css/validation.css">
<link rel="stylesheet" type="text/css" href="css/jquery.mobile-1.4.5.css">
</head>
<body>
<div data-role="page" id="pageone">
<div data-role="main" class="ui-content">
<form action="" id="registerForm" name="registerForm" >
<fieldset>
<div>
<label for="username">Username</label>
<input type="text" name="username" id="username" placeholder="insert username">
</div>
</fieldset>
<input type="button" value="SAVE" onClick="javascript:mysalvareg()">
</form>
</div>
</div>

<script type="text/javascript" src="js/jquery_1.12.4.js"></script>
<script type="text/javascript" src="js/jquery.mobile-1.4.5.js"></script>
<script type="text/javascript" src="js/jquery.validate.js"></script>
<script type="text/javascript" src="js/additional-methods.js"></script>
<script type="text/javascript" src="js/validation.js"></script>

</body>
</html>

file validation.js

function mysalvareg(){
$('#registerForm').validate({
rules: {
'username': {
required: true,
minlength: 2,
maxlength: 20,
lettersonly: true
}
},
messages: {
'username': {
required: "Please enter your name",
minlength: "Name should be more than 2 characters",
maxlength: "Name should be less than 20 characters",
lettersonly: "Name should contain only letters"
}
},
});
}