February 21, 2015

Things I learnt about Vim this week: Joining lines of text.

I've been using Vim now for over a year but I'm still increasingly amazed how little I know.

This week I've been writing some documentation in markdown. Working with text that isn't a programming language like C#, Clojure or JavaScript helped me to discover a few cool Vim commands I should have known already.

Joining lines of text

Given the following block of text, when the cursor is on the first line we can use J in normal mode to join the two lines of text.

this is a line of text
and should be followed by this
becomes
this is a line of text and should be followed by this

With text spread over three lines, like below, when the cursor is on the first line we can use JJ in normal mode to join the three lines of text.

this is a line of text
and should be followed by this
and this
becomes
this is a line of text and should be followed by this and this

Obviously, we can do better than bashing the J key. Lets take the below text as an example. Vims composability means that J is just another command we can apply to word motions, or selections. With the cursor on the first line of the text we can do VGJ. V goes into Visual mode, G selects to the bottom of the document and J joins the selection.

this is a line of text
and should be followed by this
and this line

this is a line of text
and should be followed by this
and this line

this is a line of text
and should be followed by this
and this line

this is a line of text
and should be followed by this
and this line
becomes
this is a line of text and should be followed by this and this line this is a line of text and should be followed by this and this line this is a line of text and should be followed by this and this line this is a line of text and should be followed by this and this line

Thats pretty cool, since we can apply J to selections we can do more too. If we take the text block below, when the cursor is on line 3, we can enter visual mode V, select 2 lines down 2j and hit J to join the selection.

this is a line of text and should be followed by this and this line

this is a line of text
and should be followed by this
and this line

this is a line of text and should be followed by this and this line

this is a line of text and should be followed by this and this line
becomes
this is a line of text and should be followed by this and this line

this is a line of text and should be followed by this and this line

this is a line of text and should be followed by this and this line

this is a line of text and should be followed by this and this line

We can apply the same principle using something more concrete as an example. What if we had the if statement below and we'd rather just put the condition checking on one line. With the cursor positioned on the opening parentheses we can hit V%J, V to go into Visual mode, % to select to the closing parentheses and J to join the text.

if (1 == 1 &&
    2 == 2 &&
    3 == 3) {

}
becomes
if (1 == 1 && 2 == 2 && 3 == 3) {

}

Note that J joins lines and includes an additional space between them. To join lines without the inclusion of an additional space you can use gJ.

A quick mention to a Vim plugin I was using when editing markdown. vim-livedown uses a node module called livedown to preview markdown files in the browser as you edit them.

Tags: vim