by Al-amin Nowshad
How to build a CLI tool in NodeJS ?
As developers, we kind of live with CLI tools. From
cloud shells — we are using these tools everywhere. So, it’s time to make your own. We’ll use Heroku’s great oclif framework in the process.
It’s an open framework to build CLI tools quickly, and it’s provided by the well-known Heroku.
What’s gonna be built?
We’ll make a todo list command that can have four actions:
- Add a new task
- View all tasks
- Update task
- Remove a task
Initialize our project
Oclif can generate two types of projects —
- Projects that have one command.
- Projects that might have multiple commands, including nested ones.
In this article, we’re gonna need a multiple commands project, so let’s generate it:
npx oclif multi todocli
Running this command and following the instructions will initialize a fresh project named
todocli inside the current directory.
Now, let’s go inside the directory and run help:
cd todocli && ./bin/run --help
This will print the results below:
> USAGE $ todocli [COMMAND] COMMANDS hello help display help for todocli
This shows available commands and their documentation.
src directory we can find a directory named
commands. This directory holds all the commands with their relative file names. For example, if we have a command
hello we’ll have a file named
hello.js inside this directory and the command will work without any more setup. Let’s remove
hello.js as we won’t be needing it.
To store our tasks we need a storage system. For simplicity, we’ll use lowdb which is a pretty simple json file storage system. Sweet for this project ?
Let’s install it:
npm install lowdb --save
Let’s create a
db.json file inside our project root directory. This file will hold our data. Then we need to install lowdb. Now, we’ll create a file called
db.js inside the
src directory. This file will hold our database stuff.
Here, we’re simply loading the required library and file at first, then defining an empty todos array as our base collection (it’s like a table if you’re thinking like SQL databases).
oclif provides us with a smooth command generation functionality. Let’s run the following:
oclif command add
This will create a file named
src/commands directory. Let’s replace that file’s content with the code below:
The file has a few key components:
- a run function that executes the main functionality of this command,
- a description, that’s the documentation for the command, and
- flags, which describes the flags passed to the command.
Here, we have a flag named
task which has a
string type. We can run the command
./bin/run add --task="welcome task"
This command will add a task to our database and print the response of that operation.
show.js , we’re showing all the tasks in ascending order. We’ve added a little color with
chalkjs to give our command results a better look.
For simplicity, we’re now just setting tasks as
done for our update part. We’ve to just passed the task’s
id as a
./bin/run update --id=1
This will set the
done = true for the task with
id = 1 .
Removing is pretty straightforward: we pass
id as a flag, and then remove the related task from our database.
And just like that, we’ve made our very simple
todocli. Now if we want to use it like any other normal CLI tool or let our friends use it, we need to make it an npm package. So actually let’s publish it on npm.
Build and Publish to npm
First of all, make sure you have a npm account. Then you need to login running the command
Then inside the project directory run
npm run prepack
This will pack the project and make it npm-ready with a generated readme from the descriptions and flags.
Now, publish it on npm:
If everything goes well, then the module has been published on npm successfully. If it doesn’t work, check the project name and version.
Now, we can use it like any other npm tool with the global installation:
npm install -g todocli
And then anyone can just use these commands anytime, almost anywhere ?
> todocli add --task="Great task!!!"> todocli show> todocli update --id=1> todocli remove --id=1
If you’ve come this far following the whole article, congratulations ? You are awesome. Now, you can do a little task:
The id assigning of the tasks is not a proper one, can you fix it? Let me know how you solve it in the response section.
Good luck, and thanks for reading :)
oclif : https://oclif.io