[JavaScript] checks (determines) whether a link (URL) is valid (the service is available)

How can I use javascript to determine whether the requested url/link is valid (connectable and available )? Introduction There is an address book system deployed on several servers at the same time, but there is a Address Book link on the home page to link to this system. the problem is that sometimes the link to the server fails, so I hope... syntaxHighlighter. all ();

How can I use javascript to determine whether the requested url/link is valid (connectable and available )?

Introduction

There is an address book system deployed on several servers at the same time, but there is a Address Book link on the home page to link to this system. the problem is that sometimes the link points to a server with a failure, so you want to point to other servers when the server is faulty (the service is unavailable.

Solution 1: XMLHTTP

The following code is taken from the reply of meizz in [2: