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Sensible Debugging in IE 8

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One thing that caught my attention in the IE 8 notes and that eventually made me download and install it is that it will feature the Developer Toolbar which has been an add-in for previous IE versions as a built in tool. Not only that but IE 8 includes a very FireBug-like debugger that can be easily hooked up to page content.

This is a very worthwhile improvement IMHO because the debugging experience in IE has always been one of pain having to go through dialog pop ups and really to get anything useful having to run the Visual Studio script debugger. While the experience for debugging IE has dramatically improved in Visual Studio 2008 IF you are running an ASP.NET  project for debugging, the standalone debugger story still hasn't changed much.

IE 8 introduces a debugger as part of the developer toolbar:

IE Debugger

The developer tools window above can be activated from the Tool menu (or a hotkey) and once active you can easily select a source or script file from the script dropdown button (not easy to see above - the button with the link on it - the rest is obscured). You can set a breakpoint anywhere in the code and the debugger will stop on the appropriate code.

You basically click on the Start Debugging button to enable the debugger and while in there any Debugger commands in your script or script errors jump into the above debugger rather than popping up the nasty IE debugger dialog. If you're in development mode and you're working with multiple pages you simply leave the button set in debugging mode and all errors, break points and debugger keywords trigger in the debugger. Finally an easy and light weight way to do deterministic debugging in IE.

You get the familiar IE script debugger options including the detailed locals and watch windows that let you drill down nicely into any object hierarchies, the callstack window and the always useful immediate window to let you eval expressions interactively. The behaviors here are really nothing new from what you see inside of Visual Studio or even the regular IE script debugger. I think what's nice with this scenario is that it's much more easily accessible which is a big win IMHO! You've heard me bitch about the crappy script error handling and debugging experience for IE and this goes a long way towards addressing the problems.

I would like to see one additional step taken though and that is to get rid of the modal dialog if script debugging is enabled and rather have a more FireBug like model where you can see that an error occurred with a way to click the error icon and then be transported into the this developer toolbar debugger window - preferrably to the appropriate line of code as FireBug does. This is easily one of the nicest and most productive features in FireBug:

But that's probably asking for a bit much <g>...

Running IE 8

So I've been running with IE 8 for the better part of the morning today and overall I don't see much in the way of breaking content. There are a few problems with alignment and spacing defaults as always seems to be the case in almost every beta version of IE. It seems every time a beta rolls the default paragraph spacing gets hosed and I end up with small oddities where line leading run a little tight or where margins between <div> tags introduce unexpected white space. Nothing major though.

Performance of the browser is noticeably faster than IE 7 on my machine. IE 8 supposedly includes support out of the box for opening up to 6 simultaneous connections to the server to retrieve content, compared to the 2 connections default in previous versions and I think that alone is accounting for the apparently more snappy behavior as less content is queuing up.

I do see a bunch of problems however in various AJAX applications that deal with event hookups. For example the Table Editable component I posted a while back doesn't want to recognize clicks unless you click for many times in succession - somehow the click handlers are not kicking in consistently.

But that sort of thing is to be expected - it's a first beta after all and to make the transition easier IE 8 does include a button to let you run in IE 7 mode and - no surprise - running these same problem pages in IE7 mode provides the expected results:

Emulate IE7

And running in this mode seems to cause no problems whatsoever - it's a good way to run a stable environment until you need to check out behavior specifically with IE 8.

One more thing: It looks that IE 8 was happy loading all of my existing add-ins and running them fine. Specifically I run RoboForm without which I can't really live any longer and if it wouldn't have worked it would have been right back to uninstalling IE 8.


Jeff King also reports that IE 8 can provide on demand debugging for Visual Studio. If you've ever enabled script debugging just so you can use the IE debugger in your ASP.NET development cycle then this new option is for you. Simply disable script debugging in the IE advanced options. Now when you start debugging with Visual Studio 2008, VS automatically triggers IE into script debugging mode so the debugger automatically pops up on breakpoints/errors as you would expect with script debugging on. When you're done debugging the script debugging is turned back off so you're left with a 'clean' environment.

The combination of this feature plus the new developer toolbar debugger should make it possible to run with script debugging and the dreaded modal dialog off for good!

Posted in HTML  Windows  

The Voices of Reason


Bob Archer
March 06, 2008

# re: Sensible Debugging in IE 8

Dude... I'm with ya! RoboForm is Da Bomb! How do people not use it? I guess they use the same password for every site?

Now I am strongly considering installing Jungle Disk (sign up with S3) so I will be able to bu and share my robo form data between multiple PC's. If I loose RoboForm files I will be spending alot of time recovering passwords. Since I'll never be able to guess the random alpha-numeric 15 character passwords I gen and use form most sites (some sites don't all them that long.)


Bob Archer
March 06, 2008

# re: Sensible Debugging in IE 8

Oh yea... built in Dev Tool bar is great. But, I hope they can Rev it out of band with IE8!


March 06, 2008

# re: Sensible Debugging in IE 8

I don't see why it would be asking too much, I too would prefer to see errors in the status bar and I think the IE team can do it.

A Red Gate employee
March 07, 2008

# re: Sensible Debugging in IE 8

Thanks for the free publicity for pinvoke.net!


JUlie Lerman
March 07, 2008

# re: Sensible Debugging in IE 8

I was hesitating to install IE8 because of all of the complaints and I don't want it to impede my regular browsing (vs. testing out IE8).

Are you using this on your regularl machine and the IE7 compat button just makes it so you can have your cake and eat it too?



March 07, 2008

# re: Sensible Debugging in IE 8

Hi Rick

OK, I installed IE8 after reading your comments (I too had been holding off). Regret to say I have just unistalled it - it caused nothing but problems with my webapps (which use webparts) - javascript errors in the webpart manager, layout problems etc. When in IE7 emulation mode the layout works but the webparts then cause DEP exeptions!

Back to IE7 - I'll install IE8 on a virtual machine to play with.

Great blog BTW!



Rick Strahl
March 07, 2008

# re: Sensible Debugging in IE 8

@Julie - I haven't seen any major problems in the last few days. What's odd is that I see a few more JavaScript errors popping up in my own code for things that were actually broken but somehow sailed through before.

But in IE 7 mode I see behavior identical to IE 7. I'm not seeing what Simon's describing, but then I'm not using IE specific rendering anywhere (ie. Web Parts which are just plain evil <g>).

Terry Vrooman
April 21, 2008

# re: Sensible Debugging in IE 8

I like the new Developer Tools feature, very nice. I do have a major gripe though... how to turn off Visual Studio script debugging if you dont want it? Since Visual Studio '08 bypasses the "Disable Script Debugging" setting in IE, shouldn't there be an option is VS to disable this feature? We use ComponentArt client controls in our pages, and they generate alot of anonymous code. It takes VS08 90 seconds to load one of our pages in debug mode, mostly because of the crappy treeview updating implementation for the solution explorer. ( haven't they heard of BeginUpdate and EndUpdate? )

If anyone knows how to turn off script debugging in VS08, so I can use IE8, please respond!

Terry Vrooman
April 29, 2008

# re: Sensible Debugging in IE 8

I've found how to disable script debugging (per session) in Visual Studio.

1: Start debugging your website, F5
2: In the top menu, go to Debug;Windows;Processes
3: In my Processes window, there are two processes, one for IExplore:script and one for WebDev.WebServer.EXE:Managed. Right-click the IExplore:script lineitem and select Detach Process.

There you go... now script debugging is disabled in VS2008 for the rest of the debug session, and you can use IE8's script debugger for the client debugging.


July 08, 2008

# re: Sensible Debugging in IE 8

Thank you very much Terry , you have saved my time :)

July 23, 2008

# re: Sensible Debugging in IE 8

will the IE 8 debugging tools increase the possbility for SQL injection and stuff?

Omarra Byrd
February 05, 2009

# re: Sensible Debugging in IE 8

I actually love the RoboForm software myself. I use it all of the time and it takes all of the menial everyday tasks that I have to perform on my computer daily and shortens them extremely! What once took me fifteen minutes to complete now takes me only one second because RoboForm does the same task with just one click. In fact I wrote a Report about a lot of RoboForm’s capabilities for use that aren’t even touched on in the User’s Manual for RoboForm. You can get that Report here:


There is also a FREE version of RoboForm that you can download on this web page, just to test the RoboForm software out for yourself! I highly recommend it!

March 26, 2009

# re: Sensible Debugging in IE 8

Re: Disabling Script debugging.

How on earth do you turn off script debugging permanently? Turning it off on a per-session basis is not a solution for me.

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