A good article on debugging Javascript while programming with PHP & Ajax.

“Javascript is a powerful tool in the web programmers toolbox however, it’s also one of our greatest headaches. Dealing with browser inconsistencies is always a source of great pain. You test on multiple platforms, find everyone you know with a mac running safari and think you have your code locked down however it rarely always works out this way. Being able to detect javascript errors in the wild can be a great resource for you to really see how your code is performing on a day to day basis. Mozilla and IE support a powerful event handler called “onerror” used like window.onerror = function(){};”

Link: AJAX, PHP and Javascript Errors - How to get more data - Jim’s PHP Programming Paradise