AJAX in Joomla 1.5

gistfile1.php

<?php
	/*
	/com_mycomponent
	|-/views
	|  |-/response
	|     |-/tmpl
	|     |  |-default.php
	|     |  |-index.html
	|     |-view.raw.php
	*/
?>

<?php
	//default.php
	defined('_JEXEC') or die('Restricted access');
	echo $this->response;
?>

<?php
	//view.raw.php
	defined('_JEXEC') or die('Restricted access');

	jimport( 'joomla.application.component.view');

	class MycomponentViewResponse extends JView{
		public function plain($tpl=null){
			$this->setLayout('default');
			parent::display($tpl);
		}
		public function json($tpl=null){
			$this->response = json_encode($this->response);
			$this->setLayout('default');
			parent::display($tpl);
		}
	}
?>


<?php
	//somewhere in a controller
	public function check(){
		$view = &$this->getView('response','raw');
		$view->response = 'OK';
		$view->plain();
	}
?>

In your ajax call use the following base URL:

index.php?option=com_mycomponent&format=raw&

Then append the right controller & task parameters to the url, like:

index.php?option=com_mycomponent&format=raw&controller=mycontroller&task=check