declare functions about node-style-guide

[felixge]

The guide already has a bunch of examples on how functions should be declared, but they are given in the context of other rules. I wouldn't mind an explicit section for this.

[kentcdodds]

I almost always prefer function declarations over function expressions (see this). So...

function packAssets(...) {
  return packed;
} // also, notice no semicolon, that's because it's incorrect to have one here

And I generally will put all my function declarations at the bottom of the closure to make my code more readable:

module.exports = {
  packAssets: packAssets
};

function packAssets(...) {
  return packed;
}

Doesn't really buy you much when you only have one function, but after about 3 or 4 it makes it a lot easier to know what the module's api is without having to scroll at all.

Function declarations also improve your stack trace because the function has a name whereas a function expression is nameless unless you explicitly give it one, which people rarely do.

These are my opinions though, curious to hear @felixge weigh in.