Checking if a URL is broken in Javascript

Question

This question has been posted on Stack before, but none so specific as to what I'm trying to understand.

The simplest way to check if a URL is corrrect to send a http Head request. But how do you use that to specify the URL ?

I found this in a previous post :

function UrlExists(url) {
  var http = new XMLHttpRequest();
  http.open('HEAD', url, false);
  http.send();
  return http.status!=404;
}

But it doesn't seem to run in firebug for a few reasons.

My apologies ahead of time for being daft.

Answer 1

I'd recommend to use jQuery for correct cross-browser ajax requests:

function UrlExists(url, cb){
    jQuery.ajax({
        url:      url,
        dataType: 'text',
        type:     'GET',
        complete:  function(xhr){
            if(typeof cb === 'function')
               cb.apply(this, [xhr.status]);
        }
    });
}

Usage:

UrlExists('/path/script.pl', function(status){
    if(status === 200){
       // file was found
    }
    else if(status === 404){
       // 404 not found
    }
});