https://developer.mozilla.org/En/Developer_Guide/Coding_Style#Namespaces https://developer.mozilla.org/En/Developer_Guide/Coding_Styl... I'm pretty sure except

https://developer.mozilla.org/En/Developer_Guide/Coding_Style#Namespaces https://developer.mozilla.org/En/Developer_Guide/Coding_Styl... I'm pretty sure exceptions aren't used because - enabling exceptions has an effect on performance - A lot of Mozilla code is XPCOM, and if you're familiar with COM and friends you'd know that they're heavily error-code oriented.