Added ajax to a Link but its not working

Question

I added a class use-ajax to a link but Its not updating the wrapper `div. My Code is:

function custom_menu(){
  $items['testing'] = array(
    'page callback' => 'articlenodeform',
    'access arguments' => array('access content'),
  );
  $items['customajaxcallback'] = array(
   'page callback' => 'custom_ajaxcallback',
   'access arguments' => array('access content'),
  );
  return $items;
}

function articlenodeform(){
   drupal_add_library('system', 'drupal.ajax'); 
   drupal_add_js('misc/ajax.js');
   $link = l(t('Say Hello'), 'customajaxcallback/ajax', array('attributes' => array('class' => 'use-ajax')));
   return '<div>'.$link.'</div><div id="sayinghello"></div>';
}

function custom_ajaxcallback($type = 'ajax') {
  if($type == 'ajax') {
    $output = t('Hello World!');
    $command = array();
    $commands[] = ajax_command_append('#sayinghello', $output);
    $page = array('#type' => 'ajax', '#ajax_command' => $commands);
    ajax_deliver($page);
  }
  else{
    return t("Hello world in new page.");
  }
}

Answer 1

Change your link to this:

$link = l(t('Say Hello'), 'customajaxcallback/ajax', array('attributes' => array('class' => array('use-ajax'))));

class element itself must also be an array. read about it here

Answer 2

function custom_menu(){
  $items['testing'] = array(
    'page callback' => 'articlenodeform',
    'access arguments' => array('access content'),
  );
  $items['customajaxcallback/%'] = array(
   'page callback' => 'custom_ajaxcallback',
   'access arguments' => array('access content'),
    'page arguments' => array(1),
  );
  return $items;
}

function articlenodeform(){
   drupal_add_library('system', 'drupal.ajax'); 
   $link = l(t('Say Hello'), 'customajaxcallback/nojs', array('attributes' => array('class' => 'use-ajax')));
   return '<div>'.$link.'</div><div id="sayinghello"></div>';
}

function custom_ajaxcallback($ajax) {
  if($ajax == 'ajax') {
    $output = t('Hello World!');
    $command = array();
    $commands[] = ajax_command_append('#sayinghello', $output);
    $page = array('#type' => 'ajax', '#ajax_command' => $commands);
    ajax_deliver($page);
  }
  else{
    return t("Hello world in new page.");
  }
}

edit: If you noticed, there were several changes made in the code.

1. link has been changed to customajaxcallback/nojs
2. hook menu is now customajaxcallback/%
3. We pass argument 1 to the callback function custom_ajaxcallback 'page arguments' => array(1),
4. Callback function has been changed by removing the default value and making it look like this custom_ajaxcallback($ajax)

Answer 3

I did it : The problem was in my callback function :

function custom_ajaxcallback($type = 'ajax') {
  if($type == 'ajax') {
    $output = t('Hello World!');
    $command = array();
    $commands[] = ajax_command_append('#sayinghello', $output);
    $page = array('#type' => 'ajax', '#commands' => $commands); --> In this line
    ajax_deliver($page);
  }
  else{
    return t("Hello world in new page.");
  }
}