Using Vimdiff to diff two things that are not local documents

Question

Every now and then I want to diff two random things (like a source-code vs some code I find online).

I could obviously create two files locally and diff them, - but I was wondering if there was a way to open Vimdiff with two empty documents (not to be saved anywhere); where I could copy/paste the text in to diff them quickly and efficiently.

If I just write vimdiff then I just get an empty vim-editor.

Answer 1

You can diff two unwritten buffers:

• Open vim (or open a new tab in you current vim instance)
• Put your current code in one buffer or open an existing file (:e ./mySourceFile)
• Split your screen with :sp or ctrl+wv
• Open a new buffer (:e)
• Put the new code you want to diff in this new buffer
• And make a diff between the two buffers with :windo diffthis
• If you update one of the buffers update the diff with :diffupdate
• When you're done use :diffoff!

See

• :h :diffthis
• :h :diffupdate
• :h :diffoff