How to check on the client side if the site is blocked?

Question

JavaScript

Social media is blocked at work. There is a site on which buttons from social networks are installed (share, likes). So, if facebook cannot connect to its SDK, then it displays a half-page message that the server is blocked.
The question is how to check if facebook is available, and depending on this already connect or not connect the button on the client? Or maybe there are other ways to solve the problem?

Answer 1

The easiest way (if this is not the only way) is to try to suck a picture (for example, a logo).
Only I did not find a normal picture on the fb domain. I hope you succeed.

$("<img/>")
    .load(function() { console.log("VK works"); })
    .error(function() { console.log("VK closed"); })
    .attr("src", "http://vk.com/images/camera_a.gif");

PS Solution from here stackoverflow.com/questions/8571227/use-javascript...
PPS If you want, I can rewrite without jQuery

Answer 2

Use the program ala teamviawer