# Plugin Development

# Introduction

So you want to make a plugin for JD CLI?

Plugins are imported directly by the CLI, so you have the full power of the Deno ecosystem.

If you have never used Deno (opens new window) before, you might want to consider reading Deno Manual (opens new window) and a gentle introduction to the runtime and it's features.

Before developing your own plugins, you'll want to read how to install plugins.


ALL Johnny Decimal CLI Commands (except the cd command) are plugins. Even the built-in ones! You can look at the built-in commands' source code for reference (opens new window) (or even override our existing commands by using the same name)!

# Basic Structure

The easiest way to understand how plugin command works is to see an example. You can code plugins in both Javascript and Typescript. Here is an example using Javascript (or look at the released typescript version (opens new window)):

 * .jd/plugins/sublime/main.js
 * Opens a location in Sublime Text!
 * `jd sublime 20.21`
 * `jd subl 20.21`
const sublimeCommand = {
  name: "sublime",
  alias: [ "subl" ],
  usage: "jd subl <location>",
  description: "Open location in Sublime",

  async fn([str] = []) {
    const [location] = await this.findLocationsById(str);

    // Logs the location our command is using

    // Runs a global sh command `open -a "Sublime Text" {location.path}`
    await Deno.run({
      cmd: ["open", "-a", "Sublime Text", location.path],
      stdin: "piped",
      stdout: "piped",
      stderr: "piped",

export default sublimeCommand;

The structure of this Plugin Command is something like this:

property description
name Basically the key used for registering the plugin. So for this example, JD CLI will run this command if the user inputs jd sublime.
alias An array of other names you can use to call this command. So this plugin can also be used by running jd subl
usage Logged in JD CLI's internal help command. You will see these if you run jd --help.
description Logged in JD CLI's internal help command. You will see these if you run jd --help.
fn The actual command functionality. Notice the call to this. fn is bound to the JD Directory context. This is how we make it easy to interact with the JD filesystem.

# Using Directory and Location

The core of making command plugins in JD CLI is understanding the usage of Directory and Location.

# Directory

In our Sublime Plugin, you'll notice the context call await this.findLocationsById. This is using the Johnny Decimal Directory. For all plugins, this is bound to the context of the fn method.

This is the main tool you interact with to use JD utilities.

# Location

This describes a location in the JD filesystem. It includes 3 separate ids for Area, Category, and Item.

There are mainly two entities to import:

import { Location, Directory } from "https://deno.land/x/johnny_decimal/mod.ts"