Vim is a command-based text editor based on the Unix vi editor. The Editor Wars that have been going on since the early days of vi are basically about whether vi or Emacs is the better one to use. The point being that if you live in a single text editor you slowly get it set up as you want it and slowly you merge your identity with it. Many programmers claim to be much faster using vi or Emacs than with the best "code completion" feature laden modern editor.
"Whenever vim.js crashes and you see
callback function is not specified! in the browser console, congratulations, you have found one more async function at large."
The program is described as "unstable" at the moment and if you want to help with the project visit the GitHub page.
The fundamental problem with Vim in a browser is - why?