A nearly ideal Ajax request pattern using JQuery.

perfect_ajax.js

/* The "Perfect AJAX Request", credit to Kyle Schaeffer
   http://kyleschaeffer.com/development/the-perfect-jquery-ajax-request/
*/
$.ajax({
  type: 'POST',
  url: 'http://kyleschaeffer.com/feed/',
  data: { postVar1: 'theValue1', postVar2: 'theValue2' },
  beforeSend:function(){
    // this is where we append a loading image
    $('#ajax-panel').html('<div class="loading"><img src="/images/loading.gif" alt="Loading..." /></div>');
  },
  success:function(data){
    // successful request; do something with the data
    $('#ajax-panel').empty();
    $(data).find('item').each(function(i){
      $('#ajax-panel').append('<h4>' + $(this).find('title').text() + '</h4><p>' + $(this).find('link').text() + '</p>');
    });
  },
  error:function(){
    // failed request; give feedback to user
    $('#ajax-panel').html('<p class="error"><strong>Oops!</strong> Try that again in a few moments.</p>');
  }
});