You shall implement a very simple browser application in Javascript that shall allow a user to check if an entered URL exists. The user shall be able to enter an URL and the URL must then be checked
 for valid format and if the format is correct it shall be sent to a server which provides the information if the URL exists and if it is a file or a folder. You shall not implement the server side, but just mock
 it on the client. The server call shall be asynchronous.
The check for the URL format and the existence check shall be triggered as the user is typing, but the existence check shall be throttled to avoid that too many server requests are done all the time.
