HTML

<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Personal Information</title>
<link rel="stylesheet" href="css/style.css">
<link rel="stylesheet" href="css/styleMapApi.css">
<script
	src="https://ajax.googleapis.com/ajax/libs/jquery/3.2.1/jquery.min.js"></script>
	<script>
	var postPost = function(){
		alert("post");
		if($("#form-register").valid()){
   	  var xhr=$.post( "/register",{username: $("#username").val(), lastname: $("#lastname").val(), mail: $("#mail").val(), address: $("#address").val(), phone: $("#phone").val(), password: $("#password").val()})
   	   .done(function() {
   	     alert( "Whoop-Whoop" );
   	    window.location.href = '/login.html';
   	   })
   	   .fail(function() {
   		   alert("Oops!")
   		  var error = document.getElementById("error");
				error.innerHTML = xhr.responseText;
   	  	 });
		}
	};

	</script>
	</head>

<body>

	<div id="register">
		<form id='form-register'>
			<span class="fontawesome-user"></span> <input name="username"
				type="text" id="username" placeholder="Username"> <br>
			<span class="fontawesome-user"></span> <input name="lastname"
				type="text" id="lastname" placeholder="Last Name"> <br>
			<span class="fontawesome-envelope"></span> <input name="mail"
				type="text" id="mail" placeholder="Email Address"> <br>
			<span class="fontawesome-home"></span> <input name="address"
				type="text" id="address" placeholder="Address"> <br>
			<span class="fontawesome-phone"></span> <input name="phone"
				type="tel" id="phone" placeholder="Phone"> <br> <span
				class="fontawesome-lock"></span> <input name="password" id="password"
				type="password" id="password" placeholder="Password"> <br>
			<span class="fontawesome-lock"></span> <input name="pass2"
			    id="pass2" type="password" placeholder="Confirm Password">
				<input type="button" onClick="postPost()" value="Register">
        <p id="error"></p>
		</form>
	</div>
		<div id="map">
			<script src="js/mapApi.js"></script>
			<script async defer
				src="https://maps.googleapis.com/maps/api/js?callback=initMap">

			</script>
		</div>

		<script
		src="https://cdn.jsdelivr.net/jquery.validation/1.15.0/jquery.validate.min.js"></script>
	<script
		src="https://cdn.jsdelivr.net/jquery.validation/1.15.0/additional-methods.min.js"></script>
	<script src="js/index.js"></script>
</body>
</html>