We are working on a new version of this forum and in the process a bem-textarea-editor library was created. The library has
- An editor block that allows you to write text in Markdown
- A convenient toolbar (like Github)
- A preview function to check the post before sending it to the server.
It turned out well, so we decided to publish the library as open source. May be it will be useful for you too! :)
Try the block here.