Why does JavaScript only work after opening developer tools in IE once?

Question

IE9 Bug - JavaScript only works after opening developer tools once.

Our site offers free pdf downloads to users, and it has a simple "enter password to download" function. However, it doesn't work at all in Internet Explorer.

You can see for yourself in this example.

The download pass is "makeuseof". In any other browser, it works fine. In IE, both buttons do nothing.

The most curious thing I've found is that if you open and close the developer toolbar with F12, it all suddenly starts to work.

We've tried compatibility mode and such, nothing makes a difference.

How do I make this work in Internet Explorer?

Answer 1

It sounds like you might have some debugging code in your javascript.

The experience you're describing is typical of code which contain console.log() or any of the other console functionality.

The console object is only activated when the Dev Toolbar is opened. Prior to that, calling the console object will result in it being reported as undefined. After the toolbar has been opened, the console will exist (even if the toolbar is subsequently closed), so your console calls will then work.

There are a few solutions to this:

The most obvious one is to go through your code removing references to console. You shouldn't be leaving stuff like that in production code anyway.

If you want to keep the console references, you could wrap them in an if() statement, or some other conditional which checks whether the console object exists before trying to call it.