How can I handle errors in loading an iframe?

Question

I have an <iframe> that other sites can include so their users can POST a form back to my site. I'd like to handle gracefully the cases where my site is down or my server can't serve the <iframe> contents (that is, a response timeout or a 4xx or 5xx error). I tried adding an onError to the <iframe> object, but that didn't seem to do anything:

showIFrame = function() {
  var iframe = document.createElement('iframe');
  iframe.id = 'myIFrame';
  iframe.src = 'http://myserver.com/someURLThatFailsToLoad';
  iframe.onError = iframe.onerror = myHandler;
  document.body.appendChild(iframe);
};

myHandler = function(error) {
  document.getElementById('myIFrame').style.display = 'none';
  console.error('Error loading iframe contents: ' + error);
  return true;
};

If my server returns a 404 I just get the contents of the not-found page in my <iframe>. In fact, that error handler isn't ever triggered. Is there a way to make this work?

(I'm currently testing in Chrome, but I'd like it to also work for FF and IE >= 7.)

Answer 1

To detect whether your server is down or not, you can include an empty script file from your own domain. When the server is down, the onerror event handler will fire:

var el = document.createElement('script');
el.onerror = errorFunction;
el.src = "somebogusscript.js?" + new Date().getTime();
document.body.appendChild(el);

Note: don't forget to add a random string to the src attribute to avoid the client using a cached version (which could stop a look at the server at all).

Answer 2

Perhaps you could try onErrorUpdate for the event handler? I couldn't see an onError handler for iFrames. If that doesn't work, you could try onLoad and then check the source of the iframe or the title of it for a 404 message.

Such as: if (frameDoc.title == 'title the server sends for 404') {

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Source:

http://bytes.com/topic/javascript/answers/166288-catch-404-when-using-iframe

iFrame Methods: http://www.java2s.com/Code/HTMLCSSReference/HTML-Tag-Reference/iframeJavaScriptMethods.htm

iFrame Properties: http://www.java2s.com/Code/HTMLCSSReference/HTML-Tag-Reference/iframeJavaScriptProperties.htm