Add a front end Ajax handler. Props Denis-de-Bernardy. See #12400

git-svn-id: https://develop.svn.wordpress.org/trunk@13527 602fd350-edb4-49c9-b593-d223f7449a82

wp-ajax.php

@@ -0,0 +1,30 @@
+<?php
+/**
+ * Execute an AJAX action.
+ *
+ * To take full advantage of this file, call wp_ajaxurl(); in your theme
+ * or plugin while registering your front-end scripts. Doing so will make
+ * an ajaxurl variable available for use in javascripts. The ajaxurl
+ * variable will point to this file's absolute URL.
+ *
+ * In the admin area, an ajaxurl variable is always available, and points
+ * to wp-admin/admin-ajax.php instead.
+ *
+ * @since 3.0
+ */
+define('DOING_AJAX', true);
+require_once('wp-load.php');
+
+@header('Content-Type: text/html; charset=' . get_option('blog_charset'));
+
+do_action('ajax_init');
+
+$hook = !empty($_REQUEST['action']) ? 'ajax_' . $_REQUEST['action'] : false;
+
+if ( empty($hook) || ! has_action($hook) ) {
+	status_header(400);
+	exit;
+}
+
+do_action($hook);
+?>

wp-includes/link-template.php

@@ -2015,4 +2015,24 @@ function rel_canonical() {
 	echo "<link rel='canonical' href='$link' />\n";
 }
 
+/**
+ * Prints the ajax url on the front end
+ *
+ * @since 3.0
+ **/
+function _wp_ajaxurl() {
+	echo '<script type="text/javascript">',
+			"var ajaxurl = '", esc_js(site_url('wp-ajax.php')), "';",
+		"</script>\n";
+}
+
+/**
+ * Hooks _wp_ajaxurl() to wp_head
+ *
+ * @since 3.0
+ **/
+function wp_ajaxurl() {
+	add_action('wp_head', '_wp_ajaxurl', 1);
+}
+
 ?>

wp-settings.php

@@ -289,7 +289,7 @@ do_action( 'init' );
 /**
  * This hook is fired once WP, all plugins, and the theme are fully loaded and instantiated.
  *
- * AJAX requests should use wp-admin/admin-ajax.php.
+ * AJAX requests should use wp-ajax.php and wp-admin/admin-ajax.php instead.
  *
  * @since 3.0.0
  */