drupal 7 ajax framework example does not work - drupal-7

Question

I want to add one form in user profile page. So i created user-profiled.tpl.php. In that template,i just copied the example from ajax framework for testing. Here is the whole codes:
function ajax_example_simplest($form, &$form_state) {
$form = array();
$form['changethis'] = array(
'#type' => 'select',
'#options' => array(
'one' => 'one',
'two' => 'two',
'three' => 'three',
),
'#ajax' => array(
'callback' => 'ajax_example_simplest_callback',
'wrapper' => 'replace_textfield_div',
),
);
$form['replace_textfield'] = array(
'#type' => 'textfield',
'#title' => t("The default value will be changed"),
'#description' => t("Say something about why you chose") . "'" .
(!empty($form_state['values']['changethis'])
? $form_state['values']['changethis'] : t("Not changed yet")) . "'",
'#prefix' => '<div id="replace_textfield_div">',
'#suffix' => '</div>',
);
return $form;
}
function ajax_example_simplest_callback($form, $form_state) {
return $form['replace_textfield'];
}
I am confusing now. After i clicked the checkbox, nothing change in textfield. My jquery version is 1.9. Is there any other constraints?

Answer 1

The change is in description and not in textfield(I did the same error first as you did). However I have updated the code so it also shows the value in 'textfield'.
function ajax_example_simplest($form, &$form_state)
{
$form = array();
$form['changethis'] = array(
'#type' => 'select',
'#options' => array(
'one' => 'one',
'two' => 'two',
'three' => 'three',
),
'#ajax' => array(
'callback' => 'ajax_example_simplest_callback2',
'wrapper' => 'replace_textfield_div',
),
);
$number = (!empty($form_state['values']['changethis']) ? $form_state['values']['changethis'] : t("Not changed yet"));
$form['replace_textfield'] = array(
'#type' => 'textfield',
'#title' => t("The default value will be changed"),
// Not that value was changed in the description
'#description' => t("Say something about why you chose") . " '" . $number . "'",
// Also add next line if you want to see it in the text box
'#value' => $number,
'#prefix' => '<div id="replace_textfield_div">',
'#suffix' => '</div>',
);
return $form;
}
function ajax_example_simplest_callback2($form, $form_state) {
return $form['replace_textfield'];
}