How to combine 2 actions for different mode into one mapping

Question

I wonder is there any pipeline style combination key mapping in vimrc.

For example:

The command to open the NERDTree is :NERDTree and press capital B will open the bookmark list. How can I combine them into one action when I type the key storks of nb in .vimrc?

My trying:

nnoremap nb :NERDTree<Cr>B<Cr>  //not working
nnoremap nb :NERDTree<Cr> | B<Cr>  //not working
nnoremap nb :NERDTree<Cr><Esc>B<Cr>  //not working

Answer 1

you cannot use nnoremap here. Use nmap instead. This is because B is a mapping that NERDtree provides and nore means to not use an existing mapping.