Can I see changes before I save my file in Vim?

Question

I use Vim. I open a file. I edit it and I want to see what I\'ve edited before I save it.

How can I do this in Vim?

Answer 1

Changes you just edited [buffer], i.e. those that differ from last saved version (in working directory), these may differ with last index version (Git). I mapped both:

" Find diff inbetween currrent buffer and ... A{last index version} vs B{last saved version in working directory}
"  - A{last index version}: the file as you last commited it
    " git diff to vimdiff against the index version of the file:
    nnoremap gd :Gvdiff:echo "currentBuffer vs lastIndexVersion (last commited)"
"  - B{last saved version in working directory}: the file you last :w,
"   not neccesary commited it (not commited for sure if it is in NO git project)
    " https://vim.fandom.com/wiki/Diff_current_buffer_and_the_original_file
    nnoremap gd2 :DiffSaved:echo "currentBuffer vs lastSaved (not neccesary equal to last commited)"
    function! s:DiffWithSaved()
        let filetype=&ft
        diffthis
        vnew | r # | normal! 1Gdd
        diffthis
        exe "setlocal bt=nofile bh=wipe nobl noswf ro ft=" . filetype
    endfunction
    com! DiffSaved call s:DiffWithSaved()

Example of vimdiff vs Gdiff.

• vimdiff:
• Gdiff: Commiting changes, you see only Gdiff, what might, or might have same changes as vimdiff:

Furthermore, to easy vimdiff homonym file in other path:

    " vimdiff homonym file 
   nnoremap dh  :vsplit %:p:h/../__/%:t  :windo diffthis
        "E.g."$ vim /path01/proj02_pg064/processorder.php
        ":vsplit %:p:h/../proj01_pg05/%:t | :windo diffthis