Javascript OOP best practices? [closed]

Answer 1

I use such a pattern and recommend to you to use it too:

function Person(firstname, lastname, age)
{
  var self = this;
  var _ = {};

  // Private members.  
  var firstname  = firstname;
  var lastname = lastname;
  var age = age || 'unknown';

  // Private methods.
  function first_letter_to_uppercase(str) {
    return str.charAt(0).toUpperCase() + str.substr(1);
  }

  // Public members and methods.
  _.get_age = function()
  {
    return age;
  }

  _.get_name = function()
  {
    return first_letter_to_uppercase(firstname) + ' ' +
      first_letter_to_uppercase(lastname);
  }
  return _;
}

var p = new Person('vasya', 'pupkin', 23);
alert("It's "  + p.get_name() + ', he is ' + p.get_age() + ' years old.') 

Answer 2

Because you are working on a large scale project i would suggestion a javascript framework like mootools http://mootools.net/.

It has a good class and inheritance structure.

Answer 3

I always use John resig's:

http://ejohn.org/blog/simple-javascript-inheritance/

It's simple and doesn't require any frameworks to function.

Answer 4

just for your information, i think YUI provides few great tutorials on this topic

Answer 5

These are just a few quick guidelines I've come up with, if anyone else has anything meaningful to add, I've set this answer as a community wiki so it should be easy enough for you to edit.

1. Namespace your objects to ensure they will never conflict with third party JavaScript libraries.

   window['Andrew']['JS'] = {
       addEvent: function(el,evName) {/*Stuff*/},
       Rectangle: function(width,height) {/*Stuff*/}
   };

   So then you would create a rectangle object by using:

   var myRect = new Andrew.JS.Rectangle(14,11);

   And then your code will never interfere with, or be interfered by anybody else's Rectangle.
   
   
2. Use a consistent naming strategy, specifically:
   • Object names should be capitalized, everything else (variables, functions) should begin with a lower case character i.e.

     var myRect = new Andrew.JS.Rectangle(14,11);
     document.write(myRect.getArea());

   • Ensure everything is meaningful, i.e. verbs for methods, nouns + adjectives for parameters.

3. Make sure all methods and parameters are relevant to the object they belong to. e.g. In this example, the area of the rectangle can be converted to square feet using the method inSquareFeet().

   myRect.getAreaObject().inSquareFeet();

   Make sure inSquareFeet is a method of the object returned by getAreaObject() and not a method of Andrew.JS.Rectangle

4. Use constructors, or more specifically, try as hard as possible to make sure that an object doesn't need any further initialization to be used once it has been constructed, so instead of:

   var Person = function()
   {
       this.name = "";
       this.sayHello = function ()
       {
           alert(this.name + " says 'Hello!'");
           return this;
       }
   }
   
   var bob = new Person();
   bob.name = "Bob Poulton";
   bob.sayHello();

   try:

   var Person = function(name)
   {
       this.name = name;
       this.sayHello = function ()
       {
           alert(this.name + " says 'Hello!'");
           return this;
       }
   }
   
   var bob = new Person("Bob Poulton");
   bob.sayHello();

Answer 6

//Create and define Global NameSpace Object
( function(GlobalObject, $, undefined) 
{
    GlobalObject.Method = function()
    {
        ///<summary></summary>
    }

    GlobalObject.Functionality = {};

}) (GlobalObject = GlobalObject || {}, jQuery);

//New object for specific functionality
( function(Events, $, undefined)
{
    //Member Variables 
    var Variable; // (Used for) , (type)

    // Initialize
    Events.Init = function()
    {
        ///<summary></summary>
    }

    // public method
    Events.PublicMethod = function(oParam)
    {
        ///<summary></summary>
        ///<param type=""></param>
    }

    // protected method (typically define in global object, but can be made available from here)
    GlobalObject.Functionality.ProtectedMethod = function()
    {
        ///<summary></summary>
    }

    // internal method (typically define in global object, but can be made available from here)
    GlobalObject.InternalMethod = function()
    {
        ///<summary></summary>
    }

    // private method
    var privateMethod = function()
    {
        ///<summary></summary>
    }
}) (GlobalObject.Funcitonality.Events = GlobalObject.Funcitonality.Events || {}, jQuery )

// Reusable "class" object
var oMultiInstanceClass = function()
{
    // Memeber Variables again
    var oMember = null; // 

    // Public method
    this.Init = function(oParam)
    {
        oMember = oParam;

        for ( n = 1; i < oMemeber.length; i += 1 )
        { 
           new this.SubClass.Init(oMember[i]); // you get the point, yeah?
        }
    }

    this.Subclass = function()
    {
        this.Init = function() { }
    }
}

The strength to this is that it initializes the Global object automatically, allows you to maintain the integrity of your code, and organizes each piece of functionality into a specific grouping by your definition.

This structure is solid, presenting all of the basic syntactical things you would expect from OOP without the key words.

There are even some ingenious ways to set up interfaces as well. If you choose to go that far, a simple search will give you some good tutorials and tips.

Even setting up intellisense is possible with javascript and visual studio, and then defining each piece and referencing them makes writing javascript cleaner and more manageable.

Using these three methods as needed by your situation helps keep the global namespace clean, keep your code organized and maintains separation of concerns for each object.. if used correctly. Remember, Object Oriented Design is of no use if you don't utilize the logic behind using objects!