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Mimic Window. onerror in Opera using javascript

I am currently working on a web application, I have a JS logging mechanism that Handles Javascript error that are not caught by the js code inside the page. I am using window.onerror to catch all such errors and log them else where.

However, Problem is with Opera which does not have window.onerror event. one approach I could think of is, to string process all js functions code and insert try catch blocks inside those functions after body load. It does not work in many cases though, But, It at least works to some extent.

I am sure this approach sucks, But, I could not think of anything better. Please advise.

Update: For now, I am calling the code below to Catch as many errors as I could.

function OnBodyLoad()
{
        var allElements = document.getElementsByTagName("*");
        for(var cnt = 0;cnt < allElements.length;cnt++)
        {
            RegisterAllEvents(allElements[cnt]);
        }
}
function RegisterAllEvents(objToProcess){
    for(var cnt = 0;cnt < objToProcess.attributes.length;cnt++){
        if(IsAttributeAnEvent(objToProcess.attributes[cnt].name))
        {
            objToProcess.attributes[cnt].value =  'try{'+objToProcess.attributes[cnt].value+'}catch(err){LogError("'+ objToProcess.id+'"'+ ',err);}';
        }
    }
}
like image 668
kalyang Avatar asked Mar 14 '09 12:03

kalyang


3 Answers

Opera 11.60+ supports window.onerror.

Opera's Dragonfly supports remote debugging. You might be able to hack it (it's all written in JavaScript) and log errors yourself (unfortunately the protocol isn't published yet).

like image 100
Kornel Avatar answered Oct 23 '22 17:10

Kornel


you can replace Error.prototype.toString in Opera!

window.onerror = function (msg) {
  // send msg to http://errors.net/log.php, for example
  (new Image()).src = 'http://errors.net/log.php?msg=' + encodeURIComponent(msg);
};
if (({}).toString.call(window.opera) === '[object Opera]') {
 (function () {
   var x = Error.prototype.toString;
   Error.prototype.toString = function () {
     var msg = '';
     try {
       msg = x.apply(this, arguments);
       if (typeof (window.onerror) === "function") {
         window.onerror(msg, typeof (this) === 'object' ? this.stack : '', '');
       }
     } catch (e) {}
     return msg;
   };
 }());
}

seems, it doesn't work for Opera 11.50... only for early versions ...

like image 45
4esn0k Avatar answered Oct 23 '22 19:10

4esn0k


This also happens on Safari, AFAIK.

What you could certainly do is create a global try/catch block for all JS code instead of text parsing - which could be tricky if you come into things like:

(function ($){
  $(function (){
  });
})(jQuery);
like image 2
Seb Avatar answered Oct 23 '22 17:10

Seb