Once

A simple, fast scripting CLI for your projects. The CLI uses babel-node and yargs out of the box.

Setup

Global installation

yarn global add once-cli or npm i -g once-cli

once init (initialises a once target directory)

Local installation

yarn add -D once-cli or npm i --save-dev once-cli

Add the following script to your package.json:

{
  "scripts": {
    "once": "once"
  }
}

yarn once init (initialises a once target directory)

Basic Usage

The script files in your ./once directory can be called from the command line by their filename:

once <file_name> <...args>

To create a new script from a template, use once new:

once new <file_name>

Note: To run once locally, use yarn once <file_name> <...args>

Config

The ./once target directory can be modified by adding file named once.config.js in your project's root directory:

module.exports = {
  dir: "once" // change to a different folder
}

The default babel preset for scripts is @babel/preset-env. You can override this preset your own babel.config.js in the once target directory:

├── node_modules
├── once/
|   └── babel.config.js
├── src
└── package.json

Scripts

When running your script files, the default export function is executed. This function can be sync or async:

// example script file

export default async (argv) => {

  // script goes here

}

A parsed "argv" (command line arguments) is passed into the script function as an object. These arguments are parsed using yargs default parsing. To customise this parsing, add an additional export to your script file called argv:

// example script file with custom yargs config

export const argv = (yargs) => yargs.boolean(...).usage(...)

export default async (argv) => {

  // script goes here

}

Note: Do not end your yargs config with .argv such as yargs.boolean(...).argv, as outlined in the docs. once appends its own parsing to your config, so this needs to be left open.

A complete example of a script is shown below:

// custom yargs config (see http://yargs.js.org/)
export const argv = (yargs) => yargs
  .default('n', 10)
  .usage('Usage: $0 -n [num]')
  .help('h')

// async script function which counts n seconds and logs to stdout
export default async (argv) => {

  const {n} = argv

  console.log(`counting to ${n}`)

  for (let i = 1; i <= n; i++) {

    await sleep(1000)
    console.log(i)

  }

}