ToC conditional tags: if has headings or not

Are you using the auto insert? If you are you can hook into the ez_toc_maybe_apply_the_content_filter filter. It has one parameter which returned a bool (true|false).

I hope this helps!

Thank you Steven for your suggestion but I think it is just one step to solve my issue. I use this code, and I succed to have a positive effect:

<?php 
$toctoc = apply_filters( 'ez_toc_maybe_apply_the_content_filter', 'true' );
if($toctoc==true ) { ?>
<a class="to-the-top" href="#ez-toc-container" title="Back to Contents">
<span class="to-the-top-long"><?php printf( __( 'Contents %s', 'twentytwenty' ), '<span class="arrow" aria-hidden="true">&uarr;</span>' ); ?></span></a>
<?php } else { ?>
<a class="to-the-top" href="#wrapper" title="Go Up">
<span class="to-the-top-long"><?php printf( __( 'Up %s', 'twentytwenty' ), '<span class="arrow" aria-hidden="true">&uarr;</span>' ); ?></span></a>
<?php } ?>

Now I can have the “Up to top” on home page, categories and all other pages like before to start to change the scope of this link. But on single post it does not work. The filter return true even if there are no headings, witch for ToC module this does not mean that he can not output the table. I need something similar but to return false if the ToC module can not filter the content to output the ToC list inside. I read the code of your plugin and in the philosophy of your script this check has no place. But, maybe you can help me to use the same checking to find out if a post content has or not headings, because your module only the should do something, so there I can hook in also!

Sorry, but unless I do not understand… the code you share is wrong. You do not use the apply_filters() function, you use the add_filter() to hook into the ez_toc_maybe_apply_the_content_filter

The code you show will at all times be true because you are not actually hooking into the filter.