What's causing duplicate character entry in my web form textboxes in IE?

Question

We have a fairly robust ASP.NET app using quite a bit of AJAX, jQuery & CSS.

After opening a new instance of the browser using CTRL+N, when entering data into textboxes, if users want to enter "foobar" it dups every key they hit. So they get "ffoooobbaarr" instead.

We're not able to isolate this to a consistent debugging environment that spans machines. However, we can consistently duplicate the issue on particular box images or VM's, but not on our developer machines (of course!). We have a training center where every box has the same image and it happens consistently on them depending on the exercise. Sometimes it happens, sometimes it doesn't. Very frustrating.

There's spotty evidence around the web concerning IE6 about these issues, but not really any solutions, plus we're using IE7 & IE8.

Thoughts on how to debug this? Or maybe a link to the answer somewhere?

Answer 1

It sounds very much like double subscription - if you have a javscript subscribing to the events upon page load it will do it both when the original window is loaded as well as for the new one.

Considering that CTRL+N does not create a new environment but rather creates a new window in the existing environment it is possible that your script actually subscribes to the wrong window, I mean that the new set of handlers instead of hooking up to the new window connects to the original one. If this is the case, the events will fire twice in the orig window and not at all in the new one.

Depending on how the window is located it can be browser specific or even can depend on timing.

Answer 2

It turned out to be a window.setTimeout(); interfering with some WCF work. Those setTimeouts() are demonic and have caused problems since the dawn of the function's existence.