[Task Request] Starting layout of the mindmaps

As an R package, mindr is used to convert markdown files into mindmaps, and vice versa. It can also convert tibble dataframes into mindmaps. A brief introduction can be found in one of my previous posts: mindr: an R package that creates a markdown post out of a mind map. Thanks to the support from utopian.io!

mindr has a function markmap, which creates interactive web mindmaps with the JavaScript 'markmap' library. Here is an example:

folder <- system.file("examples/md", package = "mindr")
markmap(folder = folder, remove_curly_bracket = TRUE)

It converts the following markdown file, which is the skeleton of the bookdownplus textbook, into an interactive web mindmap:

# Basic {#basic}
## Markdown Syntax {#markdown_syntax}
### What is Markdown {#what_is_markdown}
### Basic syntax {#basic_syntax}
### Chapters {#chapters}
### Figures and tables {#figures_and_tables}
### References {#references}
### Theorems, lemma, definitions, etc. {#theorems__lemma__definitions__etc_}
### Export Word document {#export_word_document}
### Equations numbering {#equations_numbering}
## R, RStudio and bookdown {#r__rstudio_and_bookdown}
## LaTeX and Pandoc {#latex_and_pandoc}
## Workflow {#workflow}
# Simple {#simple}
# Lifestyle {#lifestyle}
## Journal {#journal}
## Poem book {#poem_book}
## Music {#music}
# Office {#office}
## Mail {#mail}
### Arguments for mail content
### Mail themes
## Calendar {#calendar}
# Academic {#academic}
## Articles {#articles}
## Thesis {#thesis}
## Poster {#poster}
## Chemistry {#chemistry}
# Advanced {#advanced}
## Chinese {#chinese}
## Mind Map {#mind_map}
## Create Your Own Templates {#customize}
# FAQ {#faq}
# Bibliography {-}

By default the child nodes of this mindmap are expanded. A user of mindr left a message, asking how to start with the child nodes collapsed, like this:

Currently, the user has to click the circle of the node to expand or collapse.

The task is to add an option to the markmap() function, which allows users to decide the starting layout of the mindmap, such as the child nodes collapsed or expanded.

Components

Once the task will be completed, the returned results of the following functions will be changed:

mindr::markmap()

PS. The example showed above looks long. I used it just because it was taken from a real book and included in the current version of mindr. After I posted this article, @tdre suggested that a smaller, more concise markdown file and mind map illustration would have been enough to get the point across in this case and made for a faster read. Thanks to @tdre. I totally agree. Here is a smaller example. A mini markdown file for testing is:

# New Projects
## What is the project about?
## Technology Stack
## Roadmap
## How to contribute?
# New Features
## What feature(s) did you add?
## How did you implement it/them?
# Bug Fixes

Save this file as test.md in a folder named /md in your work directory, and run:

markmap('md')

Then you get a mindmap in your viewer with all the child nodes expanded:

The task is to add an option/parameter to the markmap() function, so that the mindmap can start with the given child nodes collapse, such as:

or

or