Put bluntly, with Cjax, you can literally execute Javascript from PHP, and with Cjax Plugins you can execute your own custom Javascript Code through PHP. This makes it handy dandy, for you to consolidate solid functionality through your application, and easily execute without having to get your hands dirty with chunks of javascript everywhere.

Steps for creating a plugin

• Create a Javascript file under cjax/plugins/YourPlugin.js
  
  Or you may also create a directory inside plugins directory like so: cjax/plugins/YourPlugin/YourPlugin.js, In case you want to add additional css, images, or other media, etc.
  
  
• Add a function YourPlugin in YourPlugin.js
   
 function YourPlugin() {}

• Call your plugin
   
$ajax->YourPlugin()

• Replace "YourPlugin" with the name you would like your plugin to have
• Pass parameters
  You may pass strings or arrays through function parameters through your php plugin call.
   
$ajax->YourPlugin('pass strings', array('pass'=>'arrays'))

  
  Acess parameters in your JavaScript Plugin:  

    //cjax/plugins/YourPlugin.js
    function YourPlugin(string, array) {
        alert(string);
        
        //alerts all the items in your array.
        for(item in array) {
            alert(item+ ' '+array[item]);
        }
    }

  Arrays are converted to Json objects, that is how you would access them.

Hello World Plugin

PHP Code used to call plugin:
This is what hello_world.js looks like:  

function hello_world(a,b,c)
{
    //sample of importing javascript into the scope
    this.importFile('http://cjax.googlecode.com/svn/trunk/_extra/test_unit/plugins/js/test.js');
    //sample of importing css to the page
    this.importFile('http://cjax.googlecode.com/svn/trunk/_extra/test_unit/plugins/css/test.css');
    
    console.log('File base:', this.base);
    console.log('This file:', this.file);
    console.log('Paramters Passed:', a, b ,c);
}



A Plugin can stand on its own without a php class - and does not require one. However if you require more power in your plugin extra functions or ajax controllers, Or to overwrite plugin core functionality to customize your plugin even more then you might be interested in using a php class in your plugin.
Some of the functions in plugin PHP APIs are available to all plugins even if they don't have class.
These are: save, get , set, import, imports.

Steps for creating a PHP class for your plugin

• Create a PHP file under your plugin directory, name it YourPlugin.php
  
  
• Add a class YourPlugin in YourPlugin.php
  <?php 

    class  YourPlugin {
    
    }
    
?>
• Add a function __construct
  <?php 

    class  YourPlugin {
        
        function __construct()
        {
        
        }
    }
    
?>
• Call your plugin
   
$ajax->YourPlugin()

  When you call your plugin, the contructor is automatically triggered, all parameters passed in your plugin will be passed in the constructor as well.
  There are more trigger functions that trigger themselves, look in the PHP plugin API below.
• Replace "YourPlugin" with the name of your plugin

Ajax Controllers for plugins

Firstly to start using Ajax Controllers in your plugin, you'd need to create a "controllers" directory in your plugin. Then you are ready to go. The ajax framework through ajax.php automatically detends your plugin if you pass the plugin name as controller. For example: ajax.php?myPlugin/funtion1 will automatically go into your plugin and look for controllers/myPlugin.php. Class name is controller_myPlugin and function funtion1 (or any function name you pass through second parameter in the URL).