title: how to use Jquery AJAX in Joomla Components?
body: <p>i m developing site in Joomla, meanwhile i stuck in a problem,please help me in below problem</p>
  
  <p>here is my folder structure for component</p>
  
  <pre><code>htdocs/Joomla/administrator/component/com_test/test.php,controller.php
                                                models/test.php
                                                controllers/test.php
                                                views/test/view.html.php
                                                view/test/tmpl/default.php
  </code></pre>
  
  <p>now in <code>view.html.php</code> i created a form where i m using <strong>jquery ajax code for usernmae availability check</strong></p>
  
  <p>but i m not getting how do i combine all things to get the result that usename is available or not</p>
  
  <p>here is my code written on <strong>test/view.html.php</strong></p>
  
  <pre><code>&lt;script type="text/javascript"&gt;
   jQuery(document).ready(function(){
   jQuery("#username").change(function () {
      var usr = jQuery("#username").val();
      if (usr.length &gt;= 2) {
       jQuery("#status").html('&lt;img src="loader.gif" align="absmiddle"&gt;&amp;nbsp;Checking availability...');
       jQuery.ajax({
           type: "POST",
           url: "index.php?option=com_test&amp;view=check_user",
           data: "username=" + usr,
           success: function (msg) {
           jQuery("#status").ajaxComplete(function (event, request, settings) {
           if (msg == 'OK') {
              jQuery("#username").removeClass('object_error'); // if necessary
                  jQuery("#username").addClass("object_ok");
           }
           else {
                 jQuery("#username").removeClass('object_ok'); // if necessary
                 jQuery("#username").addClass("object_error");
                 jQuery(this).html(msg);
           }
         });
        }
      });
    }    
  });
  
  &lt;script&gt;
  
  &lt;form action="" method="post" name="addUserForm" id="addUserForm" &gt; 
     &lt;table width="100%" border="0" cellpadding="4" cellspacing="2"&gt;
       &lt;tr&gt;
      &lt;th &gt;User Name :&lt;/th&gt;
          &lt;td &gt;&lt;input type="text" name="username" id="username" size="50"&gt;
               &lt;span id="status"&gt;&lt;/span&gt;  
          &lt;/td&gt;
       &lt;/tr&gt;      
     &lt;/table&gt;
  &lt;/form&gt;
  </code></pre>
  
  <hr>
  
  <p>i have created below folders structure for above action , please tell me where do i mistake</p>
  
  <pre><code>view/check_user/view.html.php
  views/check_user/tmpl/default.php
  </code></pre>
  
  <p>code in <strong>check_user/view.html.php</strong></p>
  
  <pre><code>&lt;?php
  
  // no direct access
  defined('_JEXEC') or die('Restricted access');
  
  jimport( 'joomla.application.component.view');
  
  /**
   * HTML View class for the advertising component
   */
  class TestViewCheck_user extends JView 
  {
     /**
      * Default display function
      */  
      function display($tpl = null) 
      {
          $testController = new TestController();
          // Make an object of Main Model class contains Main functions
          $testModel = $testController-&gt;getModel('test');
          $userName  = JRequest::getVar('username');
          parent::display($tpl);
          }
   }
  ?&gt;
  </code></pre>
  
  <p>but when i run this code...why
  <code>http://localhost/Joomla/includes/js/joomla.javascript.js</code> file runs infinite times.. and finally give 4 error</p>
  
  <p>now what i have to modify/add more??? please just guide me ....</p>
  
  <p>refer any useful link which teach to create component step by step ...it will be very helpful for me</p>
  
  <p>Thanks a lot </p>