What's the best way to check if a website is up or not via JavaScript

Question

What is the best way to check if a site is up and running or down with JavaScript?

Answer 1

Ajax alone might not be the answer - if you're trying to check a remote server, since by default you can't access a remote server via ajax.

You can however access the server that the script resides/lives on - which means you can create some kind of script that acts as a proxy e.g. server side script that checks if the site in question is active and call that script via your ajax call.

An example (PHP/C# & VB.Net) of how to do this: http://www.cstruter.com/articles/article/2/8

As for Checking the status of the server:

C#

        string URL = "http://www.stackoverflow.com";
    WebRequest request = WebRequest.Create(URL);
    HttpWebResponse response = (HttpWebResponse)request.GetResponse();
    //if (response.StatusCode == HttpStatusCode.something

PHP

    @$headers = get_headers($url);

return (preg_match('/^HTTP\/\d.\d\s+(200|301|302)/', $headers[0]));