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Browser crashes on heavy single page pplication

We have a big single page application, that started to crash from time to time. We were trying to debug it for a while now, but unfortunately, still no results. We used traditional debugging tools, but they were not very useful - perhaps not used correctly.
The app seems to crash most often on Safari, it doesn't crash that often in Chrome, but it still does, so I can't rule out a problem with browser(s).
I have managed to get this crash report, which you can find at the end of this question, unfortunately I don't know what to look for in it. I know it's huge and I'm just throwing it at you saying "here, find a bug", but could you possibly have a look at it and give me some hint what might be wrong or what should I focus on in the report?
Here is the crash report http://pastebin.com/bNxpuS6T
Thanks

What I can see from the crash report and the source code is that your JavaScript code was trying to destroy some DOM objects while still iterating through those, which is the reason of the crash.
I guess you may want to check if any timer associated with the idle tabs is still active.
DETAILS:
The WebKit crashed at
1 com.apple.WebCore 0x00007fff83cace2d WebCore::ScriptExecutionContext::willDestroyActiveDOMObject(WebCore::ActiveDOMObject*) + 45
where the source code is (click here)
void ScriptExecutionContext::willDestroyActiveDOMObject(ActiveDOMObject* object)
{
ASSERT(object);
if (m_iteratingActiveDOMObjects)
CRASH();
m_activeDOMObjects.remove(object);
}

Find IE-breaking ECMAScript/JavaScript errors

I work on a relatively huge ECMAScript codebase (> 60,000 LOC) and we tend to struggle a bit with detecting errors for our dreaded friend Internet Explorer (especially 6 and 7).
At the moment, I've been stuck with an issue for 3 days where my RIA renders fine in Google Chrome, Firefox 3.6, Opera and Internet Explorer 8, but fails when running Internet Explorer 8 in IE7-Mode (or with a real IE-7).
My question really is: how do you do to identify code that will produce an error in IE7?
Usually I rely on JSLint and I tend to catch the usual suspects (trailing commas, I loathe you), but in this particular case I have just re-run a linter on all my code, both source and minimized, and it doesn't yield my usual suspects. So I guess I have mistakenly introduced something that IE doesn't like (who knows, maybe I got crazy and used Array.map instead of dojo.map somewhere?) and it blows up in my face, producing nice error messages that don't help me at all ("[object object]" and " is null" where it shouldn't be, so I assume there was an error up-stream that failed silently and prevented this object from being created).
I've tried having a look at the Google Closure Linter but it doesn't yield anything special, and I don't think that the Google Closure Compiler is going to be my savior either. is there any tool (command-line, web-service or other) that can parse/run code as if it were emulating IE so we can get the appropriate errors?
Any tips are appreciated.
EDIT: Thank you for your help in trying to solve my issue so far, but what I am really just asking is if there are tools that do this sort of checks, meaning validating a feature set and syntax against a particular browser. This is the sort of thing severly lacking in the JS-world in my opinion (not so much for FF or Chrome, obviously as their debuggers are a bit more helpful).
EDIT2: I eventually found the root of my problem today (after 3 days) by going through all my code changes between two branches and realizing that the problem was actually already there but never detected before and going back through even older changes to narrow down the mess and eventually end up adding console logs everywhere until I reached a point of failure (God thank emacs for its regular expression support to add logs to every single line... heavy but works...). Fun fact though: IE swallowed an error message supposed to be displayed in the try catch block originally catching the source problem and then re-throwing it. Still don't why, but if it hadn't then that would have been a lot easier to find, as it was intended for that purpose in case it broke. Weird. Might not like deep-levels of re-throw.
I'll leave the question open as for now there are no answer to the actual question.

You might try the IE8 debugger, as #galambalazs suggests; the old debugger from the IE6 era was generally not useful.
The low-level technique I've always used is to add my own try/catch blocks around large portions of the my Javascript source to narrow down the source of error. By iteratively adjusting your try/catch blocks you can do a "binary search" through your source to locate the code that's causing an exception. What you'll probably find is that there's some code that's harmless in Firefox but which IE's interpreter considers an error. (To be fair, it's usually the case that IE's strictness is justified, and that the lax behavior of Firefox is really undesirable.)
So in other words, you'd start on a Javascript source that you suspect, or perhaps you'd do this to all of your included .js files:
// top of Javascript source file foo.js
try {
// ... all the code ...
} catch (x) { alert("Error in foo.js: " + x); }
Now, if you load the page and get that alert, then you know that the error is somewhere in foo.js. Thus, you split it in half:
// top of foo.js
try {
// ... half the code, roughly ...
}
catch (x) { alert("Error in first half of foo.js: " + x); }
try {
// ... the rest of the code ...
} catch (x) { alert("Error in second half of foo.js: " + x); }
Repeat that process and you'll eventually find the problem.

You may try Microsoft Script Debugger, or Internet Explorer Developer Tools.
For complete list of what may be different in IE 8 from the older version consult with:
Internet Explorer 8 Readiness Toolkit (offical list)
especially DOM Improvements
JavaScript in Internet Explorer 8 (John Resig's post)
Also see Web Bug Track for possible quirks.
As a final note, doing console.log on every line may help you to find a particular bug in a hard way, but considering the amount of code you should really write unit test for modules. That's the only way you can make sure that your application will actually run with different inputs and conditions.

Output the rendered contents of a page on a JavaScript error

I'm having problems with getting decent JavaScript error invormation in a Production environment.
When I'm developing I can just attach a debugger and (usually) fix the problem.
When I get the same error in a production environment however at best I see is an error report that looks like this:
Error: Object doesn't support this property or method
Url: SomePage
Line: 42
Char: 13
Which doesn't help me very much - I can't see the rendered page and so I have no idea what line 42 looks like.
Is there any way for me to log the entire rendered page contents whenever an error like this occurs? (So line 42 of the output is the line where the error occured)
While I'm at it, are there any other techniques that I can use to help with getting useful error information from JavaScript (without need to break into the debugger) - failing that is there any way that I can structure my JavaScript slightly differently to help getting decent debug information?
I'm predominantly interested in IE - this is the browser that tends to cause me most problems.

I don't think you'll be able to get the exact original HTML source of the page back in all pages and all browsers.
Regarding debugging, you could use a logging library such as log4javascript (disclaimer: I wrote it) and intersperse logging calls in your code. log4javascript enables you to send logging messages back to the server via Ajax.

Unfortunately, IE has by default the most utterly useless error reporting. The script and line number reported in the error are essentially guaranteed to be absolutely wrong. You can, however, install the IE developer tool bar (for IE7 and older, it's built into IE8) from Microsoft, which can help track down the error source.

Ajax problem using MooTools/jQuery - p.onStatusChange is not a function

I get the following error in firebug in Firefox 3 with both MooTools and jQuery:
"p.onStatusChange is not a function".
I've noticed this error frequently in firebug since one of the latest updates of FF3. However, it has started appearing with code that hasn't been changed in some time and that was not reporting errors previously. The errors happens when ajax results are returned. It shows up in different applications that use separate javascript libraries, MooTools and jQuery.
Does anyone have any idea why these errors are appearing? My intuition tells me that it is something in Firefox that changed, but I can't find any information online currently. The ajax calls still work fine, but I am wary of just going with my intuition and leaving script errors in my code.
Thanks,
Jason

I get it in tabBrowser instead:
chrome://browser/content/tabbrowser.xml
(4) errors occur:
p.onStatusChange
p.onProgressChange
p.onStateChange
p.onSecurityChange
What I found was that the add-on "PDF Download" was causing these errors. The best way for me to check was to go to a page that produced the errors, turn off all the add-ons, and turn them on one-by-one (starting with Firebug). Instead of going one-by-one, I actually turned them on in lots of 3 to help identify the problem sooner.

Here is the reference for the function NsIDownloadProgressListener. It looks like it has been deprecated.

on a javascript error, how to identify method or js file with the problem?

When a javascript error occures in IE (or in other browsers) you get a popup saying that javascript error has occurred - usually this comes with a line number and some hint.
Sometimes it comes with line 0 and with no way of knowing what the problem is.
Javscript can come from HTML itself, from a js file or from JSP (and more).
Microsoft has a script debugger that helps a lot in finding where js errors are, however sometimes when a js error occurs the script debugger cannot find the code portion and thus its difficult of finding where is the root cause of the problem.
My question is whether anyone knows any way of making script debugger find the code any way (mostly happen with js code that is in JSP file), or at least include in the IE popup the method or js file where the error has occurred. (it only display the line number, and many times its line 0...).
Thanks,
Tal.

The error object which is created when an error is thrown by JavaScript is very unreliable when it comes to the source line, especially within IE. Browsers like Firefox and Safari are better at line numbers, but they are generally pointless due to minification of the files.
What is obviously of more use is getting the call stack, but due to the anonymous nature of JavaScript functions (well, that they can be anonymous) a call stack can often be hard to work out.
If you're doing a try/ catch you can do arguments.callee which will return you the method which called the current method which failed.
Here's a good example of doing a complete stack in JavaScript - http://eriwen.com/javascript/js-stack-trace/

Also developer tools included with Internet Explorer 8 is something good to trace and debug your javascript code

There is a version of Firebug called Firebug Lite that will work with Internet Explorer. It's performance is going to be based on how complex your pages are; however, for relatively lightweight pages, it should provide some insight.
I recommend this tool rather than simply using Firebug and Firefox because not all errors that occur in Internet Explorer will occur in Firefox, and so performing any debugging in that browser may not yield any results.

Firebug on Firefox is usually considered one of the best debugging tools.
On Firefox, go to
http://getfirebug.com
to get it.

This will print you a stack trace:
function Stack()
{
try
{
throw Error()
}
catch(ex)
{
return ex.stack
}
};
print( Stack() );

If all else fails (and when dealing with IE it sometimes does) you can always walk through your code with alerts. It's crude and tedious, but sometimes it's all you can do:
Simply:
var count = 0;
then sprinkle some:
alert(count++);
at strategic lines along your code and note where it stops alerting.
Lather rinse repeat until you have your line.

If using Firefox you can press Ctrl + Shift + J to bring up the JavaScript error console that is built into Firefox, which will tell you exactly what went wrong.