How to build markdown editor for my blog websites. Is it a good idea?

No need to reinvent the bicycle for seamingly popular feature.
You can make blogs with Markdown->HTML transformation using Jekyll, latter Nuxt Content or other tools with SSR support (which is required for proper SEO). The beauty of Markdown is that its CommonMark syntax is self-explanatory and concise for most documents, you can easily take any Markdown editor, including embedded solutions like MD preview in Visual Studio Code or just a plain text editor...

@vintprox cool!!👍