I'm working on a real time (as you type) JS static analyzer witch will hopefully detect these errors. So I'm interested in what sort of bugs is common.
I believe that types don't belong in a high level programming language like JS, where the JS engine decides the best type to use and optimize things like string concatenation. A good static analyzer and tests should cover most of the advantages of a strictly typed compiled language.
Don't confuse types with the implementation. Regardless of how the string concatenation works, you'll still need to make sure that you get something that sort of looks and behaves like a string. That's where the static typing comes in.
It's in an early stage and doesn't do much ATM that can't be accomplished with something like "Tern". If you drop your e-mail in your profile, I'll send you a link when I got something to show.
I believe that types don't belong in a high level programming language like JS, where the JS engine decides the best type to use and optimize things like string concatenation. A good static analyzer and tests should cover most of the advantages of a strictly typed compiled language.