Can vim's background color be changed based on the current mode?

Question

Just to make the title a bit more verbose:

Emphasis is on: "based on the current mode"

I would like the background to be one color when in normal or visual mode and in another when I can freely type (insert mode), automatically (=> probably autocmd, as mentioned in the solution below).

How can this be done the best way, that works in all modern flavors of vim (especially including terminal rendering)?

Answer 1

check autocmd

http://vimdoc.sourceforge.net/htmldoc/autocmd.html

for vim 8

:autocmd InsertEnter * set bg=light
:autocmd InsertLeave * set bg=dark

for vim version 9.0 please check

https://yianwillis.github.io/vimcdoc/doc/autocmd.html#ModeChanged

For the example in the site, you can change to relative numbering when enter visual mode

:au ModeChanged [vV\x16]*:* let &l:rnu = mode() =~# '^[vV\x16]'
:au ModeChanged *:[vV\x16]* let &l:rnu = mode() =~# '^[vV\x16]'
:au WinEnter,WinLeave * let &l:rnu = mode() =~# '^[vV\x16]'