I want to add styles to editor-style.css, based on the category the current post belongs to.

Therefore I would like to add the post classes - using get_post_class() - to the body of the TinyMCE iframe.

I've seen this question, but it's about adding classes via JavaScript, and I need it to be done via PHP so I can use get_post_class(). Neither can I use the admin_body_class filter, because that doesn't address the TinyMCE iframe.

How can I add the post's classes to the TinyMCE iframe?

1 Answer 1


The filter you're after is tiny_mce_before_init. Using this, we can hook into TinyMCE's 'init_array' and add body classes:

add_filter( 'tiny_mce_before_init', 'wpse_235194_tiny_mce_classes' );

function wpse_235194_tiny_mce_classes( $init_array ){

  global $post;

  if( is_a( $post, 'WP_Post' ) ){
    $init_array['body_class'] .= ' ' . join( ' ', get_post_class( '', $post->ID ) );

  return $init_array;


We're joining the post classes with a space to convert them from an array to a string as required by TinyMCE, and we're also checking that we do actually have a valid post object, to avoid errors if you're using TinyMCE elsewhere (such as in widgets or the like).


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