How to query headings in current document?

Questions
, ,
1

I use the bundle feature to build a website. I want to include an outline on every page, that links to the different headers on the current document. Is there a way to do that?

This document:

#document("page1.html")[
  #outline()
  = Page 1, header 1
  = Page 1, header 2
]
#document("page2.html")[
  = Page 2, header 1
  = Page 2, header 2
]

Compiles to:

<nav>
  <h2>Contents</h2>
  <ol style="list-style-type: none">
    <li><a href="#loc-1">Page 1, header 1</a></li>
    <li><a href="#loc-2">Page 1, header 2</a></li>
    <li><a href="page2.html#loc-1">Page 2, header 1</a></li>
    <li><a href="page2.html#loc-2">Page 2, header 2</a></li>
  </ol>
</nav>
<h2 id="loc-1">Page 1, header 1</h2>
<h2 id="loc-2">Page 1, header 2</h2>

Where I would have wanted:

<nav>
  <h2>Contents</h2>
  <ol style="list-style-type: none">
    <li><a href="#loc-1">Page 1, header 1</a></li>
    <li><a href="#loc-2">Page 1, header 2</a></li>
  </ol>
</nav>
<h2 id="loc-1">Page 1, header 1</h2>
<h2 id="loc-2">Page 1, header 2</h2>

I would need something like

#context outline(target: selector(heading).within(selector(document).parent(here())))

But selectors don’t have anything like a parent() method.

2

A workaround is to wrap the whole document in a context, and use here() in the outline’s target selector. It is somewhat fragile though, because there cannot be another context as the outline’s parents.

#document("page1.html", context [
  #outline(target: selector(heading).within(here()))
= Page 1, header 1
= Page 1, header 2
]) // works
#document("page2.html", context [
  #context outline(target: selector(heading).within(here()))
= Page 2, header 1
= Page 2, header 2
]) // doesn't work (outline is empty)
1 Like
3

You could query the location of the current document:

#context outline(target: selector(heading).within(
  query(selector(document).before(here()))
    .last()
    .location()
))

Because locations are unique identifiers for elements, you may use it inside within(...) :slight_smile:

2 Likes
4

See also:

3 Likes
5

ha, that’s the same exact solution! thanks for the reference :smile:

1 Like
6

That works, thank you very much. I didn’t think before() would also select the current element, shouldn’t that be specified in the documentation? I guess that’s what inclusive is for, but that isn’t very clear.

7

Actually, inclusive doesn’t matter here (you can set inclusive to false, and it produces the same output). Since the layout of the document is something like

#document[
  #context(...)
  ...
]

The document occurs strictly before the context block even if the context block is nested inside the document. Meaning, when we call .before(here()), there is a document before the start of the context block, which gets matched.

The inclusive field would be relevant in a scenario like

#document("index.html")[
  #context query(selector(document).before(label("test"), inclusive: false))
]<test>

Since in this example, once we label “index.html” with the label <test>, the document occurs at the same location as the label. This is what the documentation means with

inclusive: Whether end itself should match or not. This is only relevant if both selectors match the same type of element. Defaults to true.

But I agree that it can be a little confusing. The fact that one needs to use .location() to go from an element to an identifier for that same element could also be elaborated on, since that is a “trick” that can be easily missed.

1 Like