How do I execute Vimscript code from the current buffer?

Explanation

The :source command executes Vimscript from a file. When used with % (current file) or a visual selection, you can run code directly from your buffer — making Vim into an interactive Vimscript scratchpad.

Execute the entire file

:source %    " Execute all Vimscript in the current file
:so %        " Short form

Execute selected lines

" Select lines in visual mode, then:
:'<,'>source

" Or for a specific range:
:10,20source

Practical uses

" Reload your vimrc without restarting
:source ~/.vimrc
:source $MYVIMRC

" Test a function you're writing
" Write the function in a buffer, select it, source it
function! MyHelper(text)
  return toupper(a:text) . '!'
endfunction
" Select above, :'<,'>source, then test:
:echo MyHelper('hello')    " → HELLO!

" Apply a temporary setting
:source    " (with visual selection of 'set cursorline')

Interactive development workflow

1. Open a .vim file or scratch buffer
2. Write your Vimscript function or configuration
3. Select the code and :source it
4. Test it immediately
5. Iterate and re-source

Tips

• :source runs each line as an Ex command
• For Lua (Neovim): use :luafile % or :lua << EOF ... EOF
• $MYVIMRC is a built-in variable pointing to your vimrc
• Use this workflow for developing custom functions, testing mappings, or debugging config
• Neovim users can also use :source with Lua files (.lua)
• Documented under :help :source