问如何在上传中添加进度条(PHP)

EN

global $post;
/*Video Uploading*/

if ( isset($_FILES['upload_attachment']) ) {
    $count = '0';
    $files = $_FILES['upload_attachment'];

    foreach ($files['name'] as $key => $value) {
        if ($files['name'][$key]) {
            $file = array(
                'name'     => $files['name'][$key],
                'type'     => $files['type'][$key],
                'tmp_name' => $files['tmp_name'][$key],
                'error'    => $files['error'][$key],
                'size'     => $files['size'][$key]
            );

            $_FILES = array("upload_attachment" => $file);

            foreach ($_FILES as $file => $array) {
                $newupload = betube_insert_attachment($file,$post->ID);
                $attachvideo = wp_get_attachment_url( $newupload);
                add_post_meta($post_id, 'jtheme_video_file', $attachvideo);
                add_post_meta($post_id, '_video_thumbnail', $newupload);
                set_post_thumbnail( $post_id, $newupload );
                $count++;
            }
        }
    }
}