Vim Tips: What You Didn't Know About the J Command

Check out the YouTube Video here.

Take this example:

const person = {
  name,
  age,
  height,
  shoeSize
};

It's fairly easy to digest, but ESLint and Pretier are nagging to make this into a single line. If you were to fix this by hand, it becomes very complex pretty quick. There are several ways to do this, but a common way would be to place your cursor on the 2nd line, and backspace through all the whitespace until it's in the correct position.

Let me propose using the J command.

Definition straight from the docs (:help J):

*J*
J          Join [count] lines, with a minimum of two lines.
           Remove the indent and insert up to two spaces (see
           below).  Fails when on the last line of the buffer.
           If [count] is too big it is reduced to the number of
           lines avdfilable.
                            *v_J*
{Visual}J  Join the highlighted lines, with a minimum of two
           lines.  Remove the indent and insert up to two spaces
           (see below).

What would have taken a few keystrokes to join one line, has now been reduced to a single keystroke.

Let's see this again with the new J command. You can now simply press JJJJJ (Jx5) and you will be able to join the entire object onto one line.

If you have relative line numbers, you can execute exactly how many J commands are needed. I'm not sure why this one requires the command 6J insteady of 5J. Feel free to tweet me if you guys know the answer to that one.

Even better yet, you can pair this with any kind of visual command.

Comments, when joined will still have the pesky comment leader characters. To remove those characters, add this to your .vimrc.

" remove comment leaders when joining lines
set formatoptions+=j