tab - Why can't I map shortcut keys in vim?

Question

I have been tinkering with vim recently, but I encountered a problem:

I want to use shortcut keys for switching tab commands map, so I added this sentence to my ~/.vimrc file:

map <F5> :tabnext<CR>

Nothing happened after saving ~ Why is this? consult!

Answer 1

1. If you are in insert state, you need to esc first
2. Have you opened a lot of tabs?
3. Buffer is preferred in vim
4. ctrlp is a good plug-in
5. NERDTree is also a good plug-in. . . .