Notes
TL;DR
If you use Setup El, add the following configuration.
Motivation
On this blog, I mainly write articles in MDX and generate HTML with Next.js. I use Emacs when writing articles.
I use nerd-icons-dired to display file icons in Emacs, but the default configuration does not show icons for MDX files. It is not a big problem, but seeing only a white square icon when switching buffers or viewing dired feels dull, so I looked into how to customize it.
Configuration
This is done by adding a value to nerd-icons-extension-icon-alist in nerd-icons, not nerd-icons-dired.
Install nerd-icons and nerd-icons-dired using the method that matches your package manager.
If you want a package-manager-agnostic version, it looks like this.
You can find icon names by running M-x nerd-icon-insert, which shows a list of icons.
If you want to match existing icons, refer to the nerd-icons code.