Shortcut for console.log in Spacemacs

Introduction

Against all best practices, I debug js code using console.log. I also use Spacemacs, which I wrote about before. Typing this code over and over again became tedious, so I wanted a way to make it faster.

// I wanted to type a variable
foo

// And easily turn it into this
console.log("foo", foo)

This was one of the first things I ever wrote in elisp, so here's what I learned.

Defining a new binding

Because I only wanted this key binding to apply when using rjsx-mode, I used the function spacemacs/set-leader-keys-for-major-mode. This established a new key binding behind the leader key, so it can be accessed like all other Spacemacs mode bindings (through SPC m or ,).

The code for my binding ended up looking like this:

(spacemacs/set-leader-keys-for-major-mode 'rjsx-mode "l" 'insert-console-log)

'insert-console-log is the symbol for a function that I defined separately. I found this useful because then I could reevaluate the function definition. Since the keybinding was still set up, I could then test it without needing to close any files or restart emacs.

Function definition

This is what my insert-console-log function looks like.

(defun insert-console-log ()
  "Insert console.log of the variable at point."
  (interactive)
  (let ((beg nil)
        (end nil))
    (back-to-indentation)
    (setq beg (point))
    (end-of-line)
    (setq end (point))
    (kill-region beg end)
    (insert (format "console.log("%s", %s)"
                    (car kill-ring)
                    (car kill-ring)))))

This function first initializes two variables, beg and end. After that it moves the cursor to the start of the current line (minus indentation) with back-to-indentation, and sets beg to the cursor position there. After that it moves to the end of the line and sets end to the cursor position there. kill-region copies the text between those two positions to the kill ring and deletes it from the buffer. The final insert adds a console.log statement to the buffer, interpolating the first item from the kill ring twice ( with ( car kill-ring )).

Credit where credit is due

I had tried to dig into elisp and Spacemacs code a few times before and had always found it challenging. On one of my favorite podcasts the host often talks about how paying for coaching to help you improve at skills is always a great investment.

Codementor is a platform that allows you to hire programmers to coach you in specific areas. Most of what I learned for this key binding came from pairing with Rudolf Olah, who was very patient when I got frustrated during the learning. Thanks Rudolf!