The state of documentation of Express 4 is not great. You have to look at the source code to see how it really works most times, or read someone's blog about how it used to work in Express 3 - but no longer does.

Whose decision was it to go from a "batteries included" web server module to one where users had to assemble a bunch of ad-hoc third party components to make a usable web server? I'm looking at you, body-parser.