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javascriptconstructormodule-pattern
Fergal
Fergal

Reputation: 2474

JavaScript module pattern vs Constructor with methods defined in constructor

From a single instance and a multiple instance point of view, why would I write all those extra lines of code following the Module Pattern vs just using a standard Constructor with methods and properties defined in the constructor body?

Module Pattern sample : http://jsfiddle.net/T3ZJE/1/

var module = (function () {
    // private variables and functions
    var foo = 'bar';

    // constructor
    var module = function () {
    };

    // prototype
    module.prototype = {
        constructor: module,
        something: function () {
        }
    };

    // return module
    return module;
})();

var my_module = new module();

console.log(my_module)


Constructor sample : http://jsfiddle.net/EuvaS/2/

function Module(){

    // private variables and functions
    var foo = 'bar';

    //public methods
    this.something = function () {

    }        
}

var my_module = new Module();

console.log(my_module);

To me the end result is pretty much the same. Both can have public properties and methods, both can have "private" variables and methods which can be accessed by the public methods.

Both will define public / prototype methods once for a singleton, both will define them multiple times for multiple instances / clones of the object.

Am I missing something? What is the difference?

Upvotes: 11

Views: 13001

Answers (2)

David Lee
David Lee

Reputation: 11

Nothing special difference. But I am not sure what is the point of the module pattern in this example. You don't need to include the constructor in the module. Constructors should be used like the second style. But it is better for the methods to be defined in its prototype object unless you need to have it for each instance.

Again in terms of purpose, I do not think that the module pattern here is proper way.

Upvotes: 0

Damp
Damp

Reputation: 3348

In the first example, foo will be a static variable common to all instances of module(). Meaning, all instances will reference the same variable.

In the second example, foo is different for each Module() instance.

Apart from that, I don't see any difference.

Upvotes: 18

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