Hide submit button if user does not fill required fields
https://jsfiddle.net/w0pohLeb/3/
<style>
#login {
display: none;
}
</style>
<input type="text" id="username" required="true">
<input type="email" id="email" required="true">
<button type="submit" id="login">
Sign Up
</button>
<script>
$(document).ready(function() {
if ($('#email').val().trim().length === 0 && $('#username').val().trim().length === 0) {
$('#login').hide();
}
else {
$('#login').show();
}
$("#email, #username").keyup(function () {
if ($('#email').val().trim().length === 0 && $('#username').val().trim().length === 0) {
$('#login').hide();
}
else {
$('#login').show();
}
});
});
</script>