Exploding JavaScript Cagematch 24 [Brazil]

What:
Webdev writes a metric-butt-ton of JS these days, and a mix of styles, legacy code, and time pressure can result in a pretty messy code base. Let's discuss strategies to keep our code svelte and sexy. Possible topics include knowing when to go MVC, linting, testing (see kumar I remember this sometimes), design patterns, event driven code, and really whatever else people want to bring to the table. I'm not looking for one unified standard for all Mozilla projects, but an externally publishable document about How We Do It would be awesome.

Should I come to this?
Do you write JavaScript that is bound for public consumption on a Mozilla web property, or love someone who does? Then yes, you should come.

Goals:
Let's come out of this with a list of potential best-practices (these need not be global to all webdev projects) for large JS codebases.