Auto-link HTML H2 elements and include them in the TOC about framework HOT 1 CLOSED

Investigating…

The code actually does find the H2 elements. The problem is that when an H2 is specified in HTML, unlike Markdown it isn’t automatically wrapped in a header anchor; we use markdown-it-anchor to do that for Markdown. So the code finds the H2 elements, but then ignores them because they don’t have an <a href class="observablehq-header-anchor"> inside.

So, you can declare a heading that is visible in the TOC like so:

<h2 id="this-is-a-test" tabindex="-1">
  <a class="observablehq-header-anchor" href="#this-is-a-test">This is a test</a>
</h2>

(The tabindex attribute is optional but recommended.)

To do this automatically, we’d need to duplicate the behavior of markdown-it-anchor for HTML H2 elements: automatically wrap them in an anchor and compute a unique slug based on the text content of the heading. Another possibility is that we require you to specify the id attribute when specifying an H2 element in HTML (so that there is no ambiguity as to what the link should be); in general we treat HTML as a lower-level API to Markdown.

Probably this means we should not use markdown-it-anchor so we don’t have two code paths for generating heading links; instead, we let markdown-it render the ## as a vanilla H2, and then we use the same code path for turning H2 into heading links regardless of whether it was specified as HTML or as Markdown.

from framework.