If the line consists of boilerplate code, I will allow it to go over 120-160 chars most of times. The idea is to just get that code out of sight, as nobody should have to read it anyway. If it's important, I will break the line up. If not - like a long exception message that gets constructed with bunch of context information - I'll let it grow out of window. It's not something you will need to look at, read and grok every day. And I am happy to have it out of sight most of time.
I break up lines when thinking about stepping through them in debugger (though javascript debuggers seem to be able to step statement by statement, not line by line).