Contributing

Style & Formatting

In general, Prettier is used. See the Prettier installation and basic instructions for more information.
Though you'll see a lot of older style callback code, please utilize modern JavaScript. ES6 classes, arrow functions, and builtins.
There is almost never a reason to use var. Prefer const where you can and and let otherwise.
Save with UNIX line feeds, UTF-8 without BOM, and tabs set to 4 spaces.