detect iframe load error

Question

I am loading a user-selected page into an iframe using the src property. If the load fails, I would like to report the problem in terms that will make sense to the user. iframe

Answer 1

Late to the party, but I've managed to crack it:

At first, I thought to do an AJAX call like everyone else, except that it didn't work for me initially, as I had used jQuery. It works perfectly if you do a XMLHttpRequest:

var url = http://url_to_test.com/
var xhttp = new XMLHttpRequest();
xhttp.onreadystatechange = function() {
    if (this.readyState == 4 && this.status != 200) {
        console.log("iframe failed to load");
    }
};
xhttp.open("GET", url, true);
xhttp.send();

Edit:
So this method works ok, except that it has a lot of false negatives (picks up a lot of stuff that would display in an iframe) due to cross-origin malarky. The way that I got around this was to do a CURL/Web request on a server, and then check the response headers for a) if the website exists, and b) if the headers had set x-frame-options.

This isn't a problem if you run your own webserver, as you can make your own api call for it.

My implementation in node.js:

app.get('/iframetest',function(req,res){ //Call using /iframetest?url=url - needs to be stripped of http:// or https://
   var url = req.query.url; 
    var request = require('https').request({host: url}, function(response){ //This does an https request - require('http') if you want to do a http request
        var headers = response.headers;
        if (typeof headers["x-frame-options"] != 'undefined') {
            res.send(false); //Headers don't allow iframe
        } else {
            res.send(true); //Headers don't disallow iframe
        }
    });
    request.on('error',function(e){
       res.send(false); //website unavailable
    });
    request.end();
});