I remember having a bug once in (I think) IE8 where I had a comma after the last element an an array (like the 'greatarray' shown in this article.
The browser didn't accept a comma after the last element in an array and IIRC the compiler breaks so badly that it puts the reported error at line 1 character 1, possibly for a different file entirely.
Spent a LONG time on that.
I kind of reject his assertion that JavaScript without semi colons is "better code"
The logic, flow, maintainability, understandability, performance and, actually doing the right thing all make for better code.