using jquery ajax with codeigniter

[eluser]benton.snyder[/eluser]

Code:

var usernameRequest = $.ajax({
  type: "POST",
  url: "http://127.0.0.1/index.php/ajax/username_taken",
  data: { username:username },
  dataType: 'html'
});

// successful ajax response
usernameRequest.done(function(result) {
alert("Success!");
});

// failed ajax response
usernameRequest.fail(function(jqXHR, textStatus) {
alert("ajax request failed: " + textStatus);
});