Untitled

<!DOCTYPE html>
<html>
<body>

<form action="/action_page.php">
First name: <input type="text" name="FirstName" value="Mickey" id="NameInput"><br>
Last name: <input type="text" name="LastName" value="Mouse" id="LastNameInput"><br>
<input type="submit" value="Submit" onclick="FunctionJS()">
</form>
<script>
function FunctionJS()
{
    var name = document.getElementById("NameInput").value;
    var lastName = document.getElementById("LastNameInput").value;
    alert("name: " + name + " lastName: " + lastName);
}
</script>

</body>
</html>