modulePattern.js

function myThing(){
  // data hiding
  var collection = [];
  var api = {};
  api.methodOne = function(params){
    collection.push(params.argument);
    //...
  };
  api.methodTwo = function(params){
    var something = api.methodOne(stuff);
    //...
  };
  return api;
}


Alternative approach

function MyModule() {
    // Items is "hidden" from implementors
    var items = [];

    // A specific interface to items is provided
    // Implementors cannot access items directly
    return {
        pop: function() {
            return items.pop();
        },
        push: function(item) {
            return items.push(item);
        }
    }
}

Module pattern (compared to Constructor)