你可以先试试这个。

1. 更改此<span class="id_53">Display Post Image</span>
至<span class="id_53" data-id="53">Display Post Image</span>

2. 创建您的js文件

$(function () {
    // click event example
    $(\'.id_53\').on(\'click\', getThumb);

    // call the ajax
    function getThumb() {
        $.post( \'http://path/wp-content/themes/your-theme/ajax-file.php\' , \'my_id=\'+$(this).attr(\'data-id\') , showThumb );
    }

    // get image source
    function showThumb(e) {
        $(\'#img_in\').style({\'background-image\':e});
    }

});

// for external files
include( \'../../../wp-load.php\' );

// get your variable
$my_id = intval( $_POST[\'my_id\'] );

// get thumbnail ID
$thumb_id = get_post_thumbnail_id( $my_id );

// get path of thumbnail
$img = wp_get_attachment_image_src( $thumb_id, \'full\' );
echo $img[0];