jQuery - .ajax() call example

gistfile1.js

//load example
p = {
      username: username,
      ext: ext
};
$('#defUsernameVal').load("<?= site_url('ams/checkUsername') ?>",p);
 
 
//post example
$.post("ajax.php", { api: "Report", f: "exportToCsv"},
        function(data) {
		//alert(data);
		$("#print_data").val(data);
		("#print_form").submit();
	});
 
 
//ajax example with json return
var p = {lastname: searchStr};
 
$('.waiting_pannel').show();
$.ajax({
                url:		"<?= site_url('ams/search_user_lastname') ?>",
                cache:		false,
                data: 		p,
                type: 		'POST',
                dataType: 	'json',
                success:  	function(json) {
			var currentUser;
 
			if (jQuery.isEmptyObject(json))
		        {
			    record += "no record found for this search criteria";
			}	
			else
			{																			
			    for (a in json)
			    {
			         alert(json[a].sid);
                            }
			}
               
                        $('.waiting_pannel').hide();
               }
});