检测URL阻止的js ajax

I like to know if we can detect with JS (Ajax for example), the blocking of a website in a network (eg Youtube). The idea is whether Youtube is blocked I display an image instead of video.

thank you,

In ajax you could catch error from the link and act in such cases. In most cases when a site is blocked you will get an timeout, having this in mind here is an example of handling such cases:

$.ajax({
    url: "/some/youtube/url/",
    type: "GET",
    timeout: 1000,
    success: function(response) {
         // Site is not blocked
         alert(response); 
    },
    error: function(x, t, m) {
        // Site is blocked probably
        if(t==="timeout") {
            alert("got timeout");
        } else {
            alert(t);
        }
    }
});​