How to detect page loading error from extension?

Question

Is there a way to detect if tab shows 'error page'?

I mean, for example, if user enters any http://non-existing-url.com or just site is unavailable.

Anything similar to Chrome's webNavigation.onErrorOccured event.

If there is no similar event, perhaps there is a way to check Tab http status (200, 404, 502, 0, etc...)?

Answer 1

Whoops didn't see this topic. Here is how you can do it look for about:neterror load

from: mozillaZine :: Detecting “problem loading page” in firefox

have to read the docuri through the webNavigation of the browser. because the window.location is different

anyways the docuri is real nice when an error it happens. it clearly tells you whats wrong with it in the e parameter. theese are examples of some docuris that load:

about:neterror?e=dnsNotFound&u=http%3A//www.cu.reporterror%28%27afew/&c=UTF-8&d=Firefox%20can%27t%20find%20the%20server%20at%20www.cu.reporterror%28%27afew.

about:neterror?e=malformedURI&u=about%3Abalk&c=&d=The%20URL%20is%20not%20valid%20and%20cannot%

you can see the first one is dnsNotFound and the second one is malformedURI

var listenToPageLoad_IfProblemLoadingPage = function(event) {

    var win = event.originalTarget.defaultView;
    var webnav = win.QueryInterface(Ci.nsIInterfaceRequestor).getInterface(Ci.nsIWebNavigation);
    //console.log('webnav:', webnav, 'webnav of selectedtab:', window.gBrowser.webNavigation);
    var docuri = webnav.document.documentURI; //can also try event.originalTarget.linkedBrowser.webNavigation.document.documentURI <<i didnt test this linkedBrowser theory but its gotta be something like that
    var location = win.location + ''; //I add a " + ''" at the end so it makes it a string so we can use string functions like location.indexOf etc

    if (win.frameElement) {
      // Frame within a tab was loaded. win should be the top window of
      // the frameset. If you don't want do anything when frames/iframes
      // are loaded in this web page, uncomment the following line:
      // return;
      // Find the root document:
      //win = win.top;
      if (docuri.indexOf('about:neterror') == 0) {
          Components.utils.reportError('IN FRAME - PROBLEM LOADING PAGE LOADED docuri = "' + docuri + '"');
      }
    } else {
        if (docuri.indexOf('about:neterror') == 0) {
            Components.utils.reportError('IN TAB - PROBLEM LOADING PAGE LOADED docuri = "' + docuri + '"');
        }
    }
}


window.gBrowser.addEventListener('DOMContentLoaded', listenToPageLoad_IfProblemLoadingPage, false);