lib.js

(function($) {
  var MyLib = {
    doSomething() {
      // ...
    }
  }
  
  // amd/umd mumbo jumbo
  // simplified for the sake of brevity
  if (typeof window !== 'undefined') {
    window.MyLib = Mylib
  }
  else {
    module.exports = MyLib
  }
}).call(this, jQuery)