JSFiddle - React, Tailwind, and code Playground

HTML

<form class="form" name="contactform" method="post" action="https://lp.outit.co.il/LA-FACE/send_form_email.php">
                   <input  placeholder="Your Name*"  type="text" name="name" maxlength="50">
                   <input placeholder="Phone *"   type="text" name="telephone" maxlength="30">                    
                   <input placeholder="Email *"   type="email" name="email" maxlength="80">
                   <input class="send" id="register" type="submit" value="Send" disabled="disabled">
 
                   <p>* = Requierd fields</p>
                </form>

JavaScript

$(document).ready(function(){
$('form > input').keyup(function() {

var empty1 = false;
$('form > input').each(function() {
if ($(this).val() === '') {
 empty1 = true;
}
});

if (empty1) {
$('#register').attr('disabled', 'disabled');
} else {
//$('#register').removeAttr('disabled');
     $('#register').prop("disabled", false);
}
});
});