问如何使用Javascript和AJAX在PHP文件中获得$_POST值？

EN

<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.4.2/jquery.min.js"></script>

<script type="text/javascript">
    $(document).ready(function(){
        $('tr.assoc_row').show();
        $('#settings-removed-msg').hide();
        $('#new-assoc-msg').hide();
        $('#formdeleteassoc').submit(function(e){
            e.preventDefault(); //This is working to prevent normal submission of the form.

            $.ajax ({
                type: 'POST',
                url: '<?php echo $cb_t2c_remove_all_url; ?>', //I have checked this to make sure it is the correct url for the PHP file.
                data: {removeall: 'yes' //This is the data that is NOT getting passed to the PHP file.
                },
                success: function() {
                    $('#settings-removed-msg').fadeIn('fast'); //This gets triggered.
                    $('tr.assoc_row').fadeOut('fast'); //This gets triggered
                    }
            });
        });
    });

<?php
//remove_all.php

global $wpdb;
$prefix = $wpdb->prefix;

$remove_var_dump = $_POST['removeall']; //returning NULL
var_dump($remove_var_dump); //returning NULL

if ( $_POST['removeall'] == 'yes' ) {
    echo 'This was set to yes, everything is working.';
    }
else {
    echo 'This was not set to yes, it is still not working.';
}

?>

/*
JQUERY action processed by AJAX
*/

add_action('init', 'cb_t2c_action_javascript');

function cb_t2c_action_javascript() {
?>
<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.4.2/jquery.min.js"></script>
<script type="text/javascript" >
$(document).ready(function(){
    $('tr.assoc_row').show();
    $('#settings-removed-msg').hide();
    $('#new-assoc-msg').hide();
    $('#formdeleteassoc').submit(function(e){
        e.preventDefault(); //Works to prevent normal submission of the form.

        var data = {
            action: 'cb_t2c_ajax_action',
            removeall: 'yes'
            };

        // since 2.8 ajaxurl is always defined in the admin header and points to admin-ajax.php

        $.ajax ({
                type: 'POST',
                url: ajaxurl,
                data: data,
                success: function() {
                    $('#settings-removed-msg').fadeIn('fast'); //Working now
                    $('tr.assoc_row').fadeOut('fast'); //Working now
                    }
            });

        $('#formsavesettings').submit(function(){
            $('#new-assoc-msg').fadeIn('fast'); //Working now
            });
    });
});
</script>
<?php   
}
//Add the action to process the AJAX.
add_action('wp_ajax_cb_t2c_ajax_action', 'cb_t2c_action_callback');
add_action('wp_ajax_nopriv_cb_t2c_ajax_action', 'cb_t2c_action_callback');

function cb_t2c_action_callback() {
    global $wpdb; // this is how you get access to the database
    $prefix = $wpdb->prefix;

    $remove_var_dump = $_POST['removeall']; //returning NULL
    var_dump($remove_var_dump);
    $removeall = $_POST['removeall'];

    if ( isset($removeall) ){
    $wpdb->query("DELETE FROM wp_cb_tags2cats");
    }

    die(); // this is required to return a proper result
}