Debugging JavaScript is always a problem, but even more so in IE. Things should be better in IE8 but today my focus was on IE6. The tip of the day is: when IE shows an error during loading, it will provide you with a line number. You can look for hours at the line number and not figure out what it means and where the error happened.

I found out after much puzzling that IE will show the line number where the error happened from the file. So if you load foo.js and an exception occurs on line 731, IE will tell you only the line number. You have to find out for yourself which file is the cause. Oh, and you should subtract 1 from the line number.

Why is it impossible for IE engineers to provide helpful error messages? Is it so hard to actually show the filename as well?