Markdown renderer's linkifier prepends id attribute with user-content-? #1850

trwnh commented 2025年04月16日 13:57:43 +02:00

Comment

Recently looking at https://codeberg.org/fediverse/fep/src/branch/main/fep/888d/fep-888d.md and noticed some Markdown rendering issues that I don't remember being there half a year ago or so...

For example, https://codeberg.org/fediverse/fep/src/branch/main/fep/888d/fep-888d.md#exampleB behaves like so:

Upon a fresh page load or refresh, it seemingly navigates to the correct section.

However, inspecting the HTML, we see that there are some errors.

The following Markdown input:

<section id="exampleB" resource="https://w3id.org/fep/888d/exampleB" typeof="owl:ObjectProperty">
<h3>exampleB</h3>

Produces the following HTML:

<section id="user-content-exampleB">
<h3><a class="anchor" href="#"><svg ...>...</svg></a>exampleB</h3>

Note that the id="exampleB" somehow becomes id="user-content-exampleB". This has two noticeable side effects:

1. An HTML parser no longer finds anything when searching for an element with the selector *[id="exampleB"].
2. Changing the fragment component in the URL bar and navigating there does not scroll the browser to the correct section anymore.

### Comment Recently looking at https://codeberg.org/fediverse/fep/src/branch/main/fep/888d/fep-888d.md and noticed some Markdown rendering issues that I don't remember being there half a year ago or so... For example, https://codeberg.org/fediverse/fep/src/branch/main/fep/888d/fep-888d.md#exampleB behaves like so: Upon a fresh page load or refresh, it seemingly navigates to the correct section. However, inspecting the HTML, we see that there are some errors. The following Markdown input: ```md <section id="exampleB" resource="https://w3id.org/fep/888d/exampleB" typeof="owl:ObjectProperty"> <h3>exampleB</h3> ``` Produces the following HTML: ```html <section id="user-content-exampleB"> <h3><a class="anchor" href="#"><svg ...>...</svg></a>exampleB</h3> ``` Note that the `id="exampleB"` somehow becomes `id="user-content-exampleB"`. This has two noticeable side effects: 1. An HTML parser no longer finds anything when searching for an element with the selector `*[id="exampleB"]`. 2. Changing the fragment component in the URL bar and navigating there does not scroll the browser to the correct section anymore.

Gusted commented 2025年04月16日 14:14:37 +02:00

@trwnh wrote in #1850 (comment):

An HTML parser no longer finds anything when searching for an element with the selector *[id="exampleB"].

The prefix of user-content- in the ID has been there for years, so this should not be a new problem if anyone was using such selectors.

Refreshing the page does not scroll the browser to the correct section anymore.

Please elaborate more on this issue, I am not able to reproduce the issue from this description. There's javascript code that ensures that navigating or reloading to #exampleB will scroll to #user-content-exampleB.

---

As far as I am aware this is not new behavior and is also very unlikely to change, the user-content prefix is there for security reasons.

@trwnh wrote in https://codeberg.org/Codeberg/Community/issues/1850#issue-1305878: > An HTML parser no longer finds anything when searching for an element with the selector `*[id="exampleB"]`. The prefix of `user-content-` in the ID has been there for years, so this should not be a new problem if anyone was using such selectors. > Refreshing the page does not scroll the browser to the correct section anymore. Please elaborate more on this issue, I am not able to reproduce the issue from this description. There's javascript code that ensures that navigating or reloading to `#exampleB` will scroll to `#user-content-exampleB`. --- As far as I am aware this is not new behavior and is also very unlikely to change, the `user-content` prefix is there for security reasons.

trwnh commented 2025年04月16日 18:32:04 +02:00

There's javascript code that ensures that navigating or reloading to #exampleB will scroll to #user-content-exampleB.

ah, that might be it. although i can reproduce this even when javascript is enabled.

steps to reproduce:

1. Open https://codeberg.org/fediverse/fep/src/branch/main/fep/888d/fep-888d.md
2. Append #exampleB to the URL in your browser and hit enter
3. Note that the page doesn't scroll

Happening in Firefox 138 on Linux for me.

> There's javascript code that ensures that navigating or reloading to #exampleB will scroll to #user-content-exampleB. ah, that might be it. although i can reproduce this even when javascript is enabled. steps to reproduce: 1) Open https://codeberg.org/fediverse/fep/src/branch/main/fep/888d/fep-888d.md 2) Append #exampleB to the URL in your browser and hit enter 3) Note that the page doesn't scroll Happening in Firefox 138 on Linux for me.

Gusted commented 2025年04月16日 19:03:54 +02:00

@trwnh wrote in #1850 (comment):

Append #exampleB to the URL in your browser and hit enter

Yeah this case would not be handled by the code, but is this commonly done, manually appending the hash? Shouldn't be too hard to add code for this, but prefer not to if it's not strictly needed.

@trwnh wrote in https://codeberg.org/Codeberg/Community/issues/1850#issuecomment-3835526: > Append #exampleB to the URL in your browser and hit enter Yeah this case would not be handled by the code, but is this commonly done, manually appending the hash? Shouldn't be too hard to add code for this, but prefer not to if it's not strictly needed.

trwnh commented 2025年04月16日 20:47:22 +02:00

is this commonly done, manually appending the hash?

i don't know about if anyone else does it, but i commonly do it to test if anchors work or to skip to different parts of a page when there isn't a table of contents or sticky sidebar menu of some sort.

although the id not being present in the HTML output directly is probably a bigger issue, especially for no-js users.

> is this commonly done, manually appending the hash? i don't know about if anyone else does it, but i commonly do it to test if anchors work or to skip to different parts of a page when there isn't a table of contents or sticky sidebar menu of some sort. although the `id` not being present in the HTML output directly is probably a bigger issue, especially for no-js users.

fnetX commented 2025年05月14日 12:56:18 +02:00

forgejo/forgejo#5346 is the respective upstream issue. There has been a WIP pull request that can be picked up.

https://codeberg.org/forgejo/forgejo/issues/5346 is the respective upstream issue. There has been a WIP pull request that can be picked up.