manipulate a plugins shortcode

Question

I want to add some javascript directly below content, added by another plugin's shortcode.

We are using the NextGen Gallery plugin and there are many articles containing the [nggallery] shortcode. I don't want to change all articles and I don't want to inform all authors to use another shortcode in the future. And I also don't want to modify the original plugin.

Is there a way to modify a shortcode like:

function put_script_after_nggallery_shortcode( $atts ){
 return "[nggallery $atts] <script>foo();</script>";
}
add_shortcode( 'nggallery', 'put_script_after_nggallery_shortcode' );

or should I hook somehow into the rendering process of the_content() to put my script directily in the_content string after [nggallery id=nnn]. Could that be done with a filter for the_content?

Answer 1

you could

remove_shortcode( 'nggallery' );

and then add it again:

function put_script_after_nggallery_shortcode( $atts ){
 global $nggShortcodes;
 $nggShortcodes->show_gallery($atts); //or otherwise duplicate the callback function
 wp_enqueue_script('special-ngg-sciprt', 'url-to-script', null, null, true);

}
add_shortcode( 'nggallery', 'put_script_after_nggallery_shortcode' );

i'm not sure my show_gallery will work, but seems logical

what script do you need to add? why not just wp_enqueue_script on its own? there isn't any reason that the script code has to be inline.

EDIT #1

Since $nggShortcodes is apparently not a global variable, we can try using object notation... or you could just copy the contents of NextGen's gallery shortcode callback if this doesn't work. Also, I added a class check to ensure that this won't break your site if NextGen is ever deactivated.

function put_script_after_nggallery_shortcode( $atts ){
   if( ! class_exists('NextGEN_Shortcodes')) return;
   NextGEN_Shortcodes->show_gallery($atts); //or paste in the callback function
 ?>

  <script type="text/javascript">
   jQuery(document).ready(function($) {
     alert('bacon');
   });

   </script>

 <?php
}
add_shortcode( 'nggallery', 'put_script_after_nggallery_shortcode' );

Answer 2

Since WordPress 4.7 you can use the do_shortcode_tag filter.

add_filters( 'do_shortcode_tag', 'wpse_106269_do_shortcode_tag', 10, 4 );
function wpse_106269_do_shortcode_tag( $output, $tag, $attr, $m ) {
  if( $tag === something ) {
    //* Do something useful
  }
  return $output;
}