本文参考了Xiaorsz的使用 jQuery 实现 wordpress 的 Ajax 留言。
前几天，为了提高评论体验，为了减轻服务器负担，我为主题添加了AJAX提交评论功能，现在分享一下方法。
首先需要在主题的function.php文件里添加一段函数：

< ?phpfunction fail($s) {    header('HTTP/1.0 500 Internal Server Error');    echo $s;    exit;}function ajax_comment(){if($_POST['action'] == 'ajax_comment') {    global $wpdb, $db_check;        // Check DB        if(!$wpdb->dbh) {            echo('Our database has issues. Try again later.');			die();        }nocache_headers();$comment_post_ID = (int) $_POST['comment_post_ID'];$status = $wpdb->get_row("SELECT post_status, comment_status FROM $wpdb->posts WHERE ID = '$comment_post_ID'");if ( empty($status->comment_status) ) {    do_action('comment_id_not_found', $comment_post_ID);    fail('The post you are trying to comment on does not currently exist in the database.');} elseif ( 'closed' ==  $status->comment_status ) {    do_action('comment_closed', $comment_post_ID);    fail('Sorry, comments are closed for this item.');} elseif ( in_array($status->post_status, array('draft', 'pending') ) ) {    do_action('comment_on_draft', $comment_post_ID);    fail('The post you are trying to comment on has not been published.');}$comment_author       = trim(strip_tags($_POST['author']));$comment_author_email = trim($_POST['email']);$comment_author_url   = trim($_POST['url']);$comment_content      = trim($_POST['comment']);// If the user is logged in$user = wp_get_current_user();if ( $user->ID ) {    $comment_author       = $wpdb->escape($user->display_name);    $comment_author_email = $wpdb->escape($user->user_email);    $comment_author_url   = $wpdb->escape($user->user_url);    if ( current_user_can('unfiltered_html') ) {        if ( wp_create_nonce('unfiltered-html-comment_' . $comment_post_ID) != $_POST['_wp_unfiltered_html_comment'] ) {            kses_remove_filters(); // start with a clean slate            kses_init_filters(); // set up the filters        }    }} else {    if ( get_option('comment_registration') )        fail('Sorry, you must be logged in to post a comment.');}$comment_type = '';if ( get_option('require_name_email') && !$user->ID ) {    if ( 6> strlen($comment_author_email) || '' == $comment_author )        fail('Sorry: please fill the required fields (name, email).');    elseif ( !is_email($comment_author_email))        fail('Sorry: please enter a valid email address.');}if ( '' == $comment_content )    fail('Sorry: please type a comment.');// Simple duplicate check$dupe = "SELECT comment_ID FROM $wpdb->comments WHERE comment_post_ID = '$comment_post_ID' AND ( comment_author = '$comment_author' ";if ( $comment_author_email ) $dupe .= "OR comment_author_email = '$comment_author_email' ";$dupe .= ") AND comment_content = '$comment_content' LIMIT 1";if ( $wpdb->get_var($dupe) ) {    fail('Duplicate comment detected; it looks as though you/'ve already said that!');}$commentdata = compact('comment_post_ID', 'comment_author', 'comment_author_email', 'comment_author_url', 'comment_content', 'comment_type', 'user_ID');if( !$user->ID ){	$result_set = $wpdb->get_results("SELECT display_name, user_email FROM $wpdb->users WHERE display_name = '" . $comment_author . "' OR user_email = '" . $comment_author_email . "'");	if ($result_set) {	if ($result_set[0]->display_name == $comment_author){	fail( __('Error: you are not allowed to use the nickname that you entered.if you are the administrator you hava to login to comment.','philna2') );	} else {	fail( __('Error: you are not allowed to use the email that you entered.if you are the administrator you hava to login to comment.','philna2') );	}	}}$comment_id = wp_new_comment( $commentdata );$comment = get_comment($comment_id);if( !$user->ID ){	setcookie('comment_author_' . COOKIEHASH, $comment->comment_author, time() + 30000000, COOKIEPATH, COOKIE_DOMAIN);	setcookie('comment_author_email_' . COOKIEHASH, $comment->comment_author_email, time() + 30000000, COOKIEPATH, COOKIE_DOMAIN);	setcookie('comment_author_url_' . COOKIEHASH, clean_url($comment->comment_author_url), time() + 30000000, COOKIEPATH, COOKIE_DOMAIN);}@header('Content-type: ' . get_option('html_type') . '; charset=' . get_option('blog_charset'));?>	//这里需要粘贴你的评论框架代码，不过相关的调用代码有所变化：	//评论ID：$comment->comment_ID	//评论者名字：$comment->comment_author	//判断评论者是否填写了网站地址：$comment->get_comment_author_url	//评论者URL：$comment->comment_author_url	//评论时间：mysql2date(__('F jS, Y'),$comment->comment_date)	//评论者e-mail：$comment->comment_author_email	//评论内容$comment->comment_content< ?php	die();}}add_action('init', 'ajax_comment');//添加AJAX评论钩子?>

如果处理评论内容里的换行符的话，$comment->comment_content需做以下处理：

< ?php$aj_order   = array("/r/n", "/n", "/r");$aj_comment_content = str_replace($aj_order,'<br>',$comment->comment_content);echo $aj_comment_content;?>

用jQuery写提交评论时的脚本，这也是关键的部分：

jQuery(document).ready(function() {    if (jQuery('#commentform').length) {    jQuery('#commentform').submit(function(){    //ID为 commentform 的表单提交时发生的函数，也就是整个留言输入框 form 的ID。		var ajaxCommentsURL = window.location.href;        jQuery.ajax({            url: ajaxCommentsURL,            data: jQuery('#commentform').serialize()+'&action=ajax_comment',                type: 'POST',            beforeSend: function() {            jQuery('#commenterror').hide();            var submit='<div id="commentload" style="display: none;background: url("img/spinner.gif") no-repeat scroll 0 50%;margin: 0 auto;">Submitting Comment...</div>';    //创建名为 submit 的字符串，稍后插入，这里的样式大家自己根据需要定义，那个背景图片自己去下哈。	     var error='<div id="commenterror" style="display: none;margin: 0 auto;">Posted comment fail.</div>';    //创建名为 error 的字符串	        jQuery('#comments').after(submit);    // 在ID为 comments 的元素后插入刚定义的 submit	        jQuery('#comments').after(error);    // 同样插入刚定义的 error                jQuery('#commentload').slideDown();  // 让submit 向下滑出            },            error: function(request) {    //发生错误时                jQuery('#commentload').hide();    //隐藏  submit                jQuery('#commenterror').show("slow").html(request.responseText); //显示 error             },            success: function(data) {                jQuery('textarea').each(function(){                    this.value='';                });                jQuery('#commenterror').hide().html();                if (!jQuery('#thecomments').length) {                jQuery('#pinglist').before('<ol id="thecomments"></ol>');}                jQuery('#thecomments').append(data);    //向ID为 thecomments 的元素添加数据，也就是整个 ol 或 ul				var new_comment = jQuery('#thecomments li:last').hide();    //让最新添加的数据隐藏				new_comment.slideDown(1000);    //再显示，这里是为了实现滑出的效果，不想要也可以直接显示                jQuery('#commentform:input').attr('disabled', true);                jQuery('#commentload').slideUp("slow");		jQuery('#messagebox').slideUp("slow");    //这是针对我模版而加的，因为我模版在没有留言时会有个 nocomment 的元素，我要让添加一条留言后他自动隐藏，要不然会矛盾，呵呵，这个可以自行选择要或不要		setTimeout(function() {                jQuery('#commentform:input').removeAttr('disabled');                }, 10000);        //这里是设置10秒之后才可以再次留言，自行设置，单位毫秒。            }        });       return false;   } );}})

注意：
脚本里的对象ID要对应主题里的评论相关框架的ID。

后续步骤：
为commentload，commenterror写CSS。

有待完善的地方：
AJAX提交后的评论序号显示为1

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