This app's feature is replace by eaf-markdown-previewer, this app don't need install, But code is worth learning
This repository provides the EAF Mermaid application for the Emacs Application Framework.
Install EAF first, then add below code in your emacs config:
(add-to-list 'load-path "~/.emacs.d/site-lisp/emacs-application-framework/")
(require 'eaf)
(require 'eaf-mermaid)