在Wordpress系统的后台，通过Chrome浏览器查看WordPress的AJAX请求。经过几次的点击，可以WP起到AJAX请求的文件主要就是wp-admin/admin-ajax.php文件。

admin-ajax.php详细的代码如下：

<?php
/*** WordPress Ajax Process Execution** @package WordPress* @subpackage Administration** @link https://codex.wordpress.org/AJAX_in_Plugins*//*** Executing Ajax process.** @since 2.1.0*/
define( 'DOING_AJAX', true );
if ( ! defined( 'WP_ADMIN' ) ) {define( 'WP_ADMIN', true );
}/** Load WordPress Bootstrap */
require_once( dirname( dirname( __FILE__ ) ) . '/wp-load.php' );/** Allow for cross-domain requests (from the front end). */
send_origin_headers();// Require an action parameter
if ( empty( $_REQUEST['action'] ) )die( '0' );/** Load WordPress Administration APIs */
require_once( ABSPATH . 'wp-admin/includes/admin.php' );/** Load Ajax Handlers for WordPress Core */
require_once( ABSPATH . 'wp-admin/includes/ajax-actions.php' );@header( 'Content-Type: text/html; charset=' . get_option( 'blog_charset' ) );
@header( 'X-Robots-Tag: noindex' );send_nosniff_header();
nocache_headers();/** This action is documented in wp-admin/admin.php */
do_action( 'admin_init' );$core_actions_get = array('fetch-list', 'ajax-tag-search', 'wp-compression-test', 'imgedit-preview', 'oembed-cache','autocomplete-user', 'dashboard-widgets', 'logged-in',
);$core_actions_post = array('oembed-cache', 'image-editor', 'delete-comment', 'delete-tag', 'delete-link','delete-meta', 'delete-post', 'trash-post', 'untrash-post', 'delete-page', 'dim-comment','add-link-category', 'add-tag', 'get-tagcloud', 'get-comments', 'replyto-comment','edit-comment', 'add-menu-item', 'add-meta', 'add-user', 'closed-postboxes','hidden-columns', 'update-welcome-panel', 'menu-get-metabox', 'wp-link-ajax','menu-locations-save', 'menu-quick-search', 'meta-box-order', 'get-permalink','sample-permalink', 'inline-save', 'inline-save-tax', 'find_posts', 'widgets-order','save-widget', 'delete-inactive-widgets', 'set-post-thumbnail', 'date_format', 'time_format','wp-remove-post-lock', 'dismiss-wp-pointer', 'upload-attachment', 'get-attachment','query-attachments', 'save-attachment', 'save-attachment-compat', 'send-link-to-editor','send-attachment-to-editor', 'save-attachment-order', 'heartbeat', 'get-revision-diffs','save-user-color-scheme', 'update-widget', 'query-themes', 'parse-embed', 'set-attachment-thumbnail','parse-media-shortcode', 'destroy-sessions', 'install-plugin', 'update-plugin', 'press-this-save-post','press-this-add-category', 'crop-image', 'generate-password', 'save-wporg-username', 'delete-plugin','search-plugins', 'search-install-plugins', 'activate-plugin', 'update-theme', 'delete-theme','install-theme', 'get-post-thumbnail-html',
);// Deprecated
$core_actions_post[] = 'wp-fullscreen-save-post';// Register core Ajax calls.
if ( ! empty( $_GET['action'] ) && in_array( $_GET['action'], $core_actions_get ) )add_action( 'wp_ajax_' . $_GET['action'], 'wp_ajax_' . str_replace( '-', '_', $_GET['action'] ), 1 );if ( ! empty( $_POST['action'] ) && in_array( $_POST['action'], $core_actions_post ) )add_action( 'wp_ajax_' . $_POST['action'], 'wp_ajax_' . str_replace( '-', '_', $_POST['action'] ), 1 );add_action( 'wp_ajax_nopriv_heartbeat', 'wp_ajax_nopriv_heartbeat', 1 );if ( is_user_logged_in() ) {/*** Fires authenticated Ajax actions for logged-in users.** The dynamic portion of the hook name, `$_REQUEST['action']`,* refers to the name of the Ajax action callback being fired.** @since 2.1.0*/do_action( 'wp_ajax_' . $_REQUEST['action'] );
} else {/*** Fires non-authenticated Ajax actions for logged-out users.** The dynamic portion of the hook name, `$_REQUEST['action']`,* refers to the name of the Ajax action callback being fired.** @since 2.8.0*/do_action( 'wp_ajax_nopriv_' . $_REQUEST['action'] );
}
// Default status
die( '0' );

这上面显示出WordPress自带的AJAX函数hook： wp_ajax_和wp_ajax_nopriv_