Add "active" classes to Book Table of Contents

This may be a little harder to do because the Book module's function is used to generate the table of contents. Figuring out which element is the current page make require replicating and reworking that function. I am looking at what needs to be done to see what is required.

Thanks for responding, bwong

If it's any help, the core "Book navigation" block does provide this:
<li class="menu-item menu-item--active-trail li-2" data-once="ul">

And just to give you an idea why it's needed, I've uploaded a partial screenshot of one book menu

For some reason that does not follow through so I added my own. Probably need to go back and figure out how they did it but 1.12 does this. The class is book-blocks-active.

Hi @bwong thanks for this great little module. It helps me saving tons of hours in reinventing the wheels.
I would like to check about version 1.12 and the new class "book-blocks-active", is this meant to show on child page of a book?
I installed the module and dropped TOC block in my content but I cant see this new class in my menu at all.
Greatly appreciate your help!

1.13 has the support in TOC. I had only implemented it in the Edit block TOC.

@bwong you are a truly legend! It's all working as intended

Thanks bwong, that's a big help