> :%s/function/module/ and no meaning is lost :).
Javascript has functions, from the function keyword. Node.js uses commonjs. In commonjs, every file is a module. You can use
module.exports = <value>;
You can access the module by using require.
var moduleValue = require("path/to/module");
It's powerful because it doesn't have the namespace collisions that Ruby has. Everything is not global all the time. modules are also an elegant way of holding private state using closures.
Having a class with a single method is the Ruby way of categorizing this method within the domain.