Defining a module in a way that will work in several different environments. This is from Acorn <https://github.com/marijnh/acorn.git>, a JavaScript parser.

acorn.js

(function(mod) {
  if (typeof exports == "object" && typeof module == "object") return mod(exports); // CommonJS
  if (typeof define == "function" && define.amd) return define(["exports"], mod); // AMD
  mod(self.acorn || (self.acorn = {})); // Plain browser env
})(function(exports) {
  "use strict";

  exports.version = "0.2.0";

  /* ... */
});

The AMD line could be written a little differently to avoid relying on the "exports" dependency:

if (typeof define == "function" && define.amd) return define("acorn", function() {
    var exp = {}; mod(exp); return exp;
}); // AMD