book-navigation.html.twig

Default theme implementation to navigate books.

Presented under nodes that are a part of book outlines.

Available variables:

tree: The immediate children of the current node rendered as an unordered list.
current_depth: Depth of the current node within the book outline. Provided for context.
prev_url: URL to the previous node.
prev_title: Title of the previous node.
parent_url: URL to the parent node.
parent_title: Title of the parent node. Not printed by default. Provided as an option.
next_url: URL to the next node.
next_title: Title of the next node.
has_links: Flags TRUE whenever the previous, parent or next data has a value.
book_id: The book ID of the current outline being viewed. Same as the node ID containing the entire outline. Provided for context.
book_url: The book/node URL of the current outline being viewed. Provided as an option. Not used by default.
book_title: The book/node title of the current outline being viewed.

core/modules/book/templates/book-navigation.html.twig