iamcco/markdown-preview.vim

Plug 'iamcco/mathjax-support-for-mkdp'
Plug 'iamcco/markdown-preview.vim'

    MarkdownPreview
    " Open preview window in markdown buffer

    MarkdownPreviewStop
    " Close the preview window and server

    let g:mkdp_path_to_chrome = ""
    " Path to the chrome or the command to open chrome (or other modern browsers).
    " If set, g:mkdp_browserfunc would be ignored.

    let g:mkdp_browserfunc = 'MKDP_browserfunc_default'
    " Callback Vim function to open browser, the only parameter is the url to open.

    let g:mkdp_auto_start = 0
    " Set to 1, Vim will open the preview window on entering the Markdown
    " buffer.

    let g:mkdp_auto_open = 0
    " Set to 1, Vim will automatically open the preview window when you edit a
    " Markdown file.

    let g:mkdp_auto_close = 1
    " Set to 1, Vim will automatically close the current preview window when
    " switching from one Markdown buffer to another.

    let g:mkdp_refresh_slow = 0
    " Set to 1, Vim will just refresh Markdown when saving the buffer or
    " leaving from insert mode. With default 0, it will automatically refresh
    " Markdown as you edit or move the cursor.

    let g:mkdp_command_for_global = 0
    " Set to 1, the MarkdownPreview command can be used for all files,
    " by default it can only be used in Markdown files.

    let g:mkdp_open_to_the_world = 0
    " Set to 1, the preview server will be available to others in your network.
    " By default, the server only listens on localhost (127.0.0.1).

" for normal mode
nmap <silent> <F8> <Plug>MarkdownPreview
" for insert mode
imap <silent> <F8> <Plug>MarkdownPreview
" for normal mode
nmap <silent> <F9> <Plug>StopMarkdownPreview
" for insert mode
imap <silent> <F9> <Plug>StopMarkdownPreview

let g:mkdp_path_to_chrome = "open -a Google\\ Chrome"
" or
let g:mkdp_path_to_chrome = "/Applications/Google\\ Chrome.app/Contents/MacOS/Google\\ Chrome"