Javascript Module Pattern

Module pattern is one of the well know design patterns in JavaScript. I did read about this pattern, for the first time, in a publication done by Douglas Crockford. Since then, I have used this pattern in many occasions in my coding.

Using a module, an interface can be presented, by hiding the implementation and the state of an object. And it's a way of having private attributes and methods. A simple implementation is given below.


var containers = (function () {

        var module = {};
    
        var default_container_width = 500; //private property

        var possible_containers_list = new Array();
        possible_containers_list[1]="comments";
        possible_containers_list[2]="respond";   

        module.list = possible_containers_list; //public property

        function getContainerWidth() {//private function
            // ...
        }

        module.hideAll = function () {//public function
           // ...
        };

        return module ;
}());


To call the public functions and to get the public property values:

containers.hideAll();
var list = containers.list;

With this pattern, the use of global variables can also be reduced.