[TOC maxLevel=2] is rendered as plain text instead of generating a table of contents

[tsungjung411]

Is this a hackmd.io issue?

• Yes, the bug happens on https://hackmd.io
• No. If it's a self-hosted CodiMD instance, please fire up the issue in the repo of CodiMD: https://github.com/hackmdio/codimd

Read our Official tutorial

It's on https://hackmd.io/c/tutorials/

or Chinese version: https://hackmd.io/c/tutorials-tw/

What's the problem

Current behaviour

[TOC] works, but [TOC maxLevel=2] is rendered as plain text and does not generate a table of contents.

Reproducible content:

[TOC maxLevel=2]

### Section
- ### Case1
- ### Case2
- ### Case3

Actual rendered result:

[TOC maxLevel=2]

It is displayed as plain text instead of being parsed as TOC syntax.

Provide steps to reproduce:

1. Go to https://hackmd.io

2. Create a new note

3. Paste the content below:

   [TOC maxLevel=2]
   
   ### Section
   - ### Case1
   - ### Case2
   - ### Case3

4. Switch to preview / rendered view

5. Observe that [TOC maxLevel=2] is shown as plain text

Here is an example: https://hackmd.io/AkRF_wKqQWqpo_MJ32Veww

Expected behaviour

[TOC maxLevel=2] should be recognized as valid TOC syntax and generate a table of contents, instead of being rendered as plain text.

Environment

I use HackMD on:

Desktop

• OS: Windows / Ubuntu 24.04 / Android 14
• Browser: Chrome 147.0.7727.56 , FireFox 143.0（64 位元）

Mobile

• Device: Xiaomi Pro 13
• OS: Android 14
• Browser: Chrome 146.0.7880.177

Additional context

The official tutorial documents [TOC maxLevel=1] as supported syntax, so this behavior appears inconsistent with the documentation.