Command Functions

Create your own node libraries that work both as node libraries and CLI tools at the same time

How it works

Step 1 - Defining our Functions - Build a Command Map

First we create an object that maps our command names to their functions

const commands = {
    favoriteColor: () => Math.random() < 0.75 ? 'purple': 'green'
}

Step 2 - Calling the Command Functions library

First install command functions as a dependency

npm install --save command-functions

Next use the CommandFunctions class to convert your functions into a library

const CommandFunctions = require('command-functions/CommandFunctions')

const commands = {
    favoriteColor: () => Math.random() < 0.75 ? 'purple': 'green'
}
const app = new CommandFunctions(commands)

// Detects whether being required or being run by the terminal
if (require.main === module) { // It's being run by the terminal
  app.runCLI()
    .then(() => {
      console.log('Finished')
      process.exit(0)
    })
    .catch(error => {
      console.error(error)
      process.exit(1)
    })
} else { // It's a module
  module.exports = app.getExports()
}

Note: How args are parsed

When being run from the command line, Command Functions will parse your arguments internally using Minimist. Minimist will automatically parse all your arguments into their closest JSON approximation. Meaning the argument "age=[1,2,3]" will now make your function receive an options object, whose age property will be an Array containing the numbers 1 through 3. Primary arguments will be passed in before the options object, meaning the input syntax for your function should look something like this

function myFunction(firstPrimaryArg, secondPrimaryArg, options={}) {...}

Providing additional command options

Instead of providing a function as the handler for a given command in your command map, you can wrap your function inside of an object, providing the function as the "handler" property. In this case the rest of the properties are treated as options. Here's an example of what a command using this syntax might look like

const commands = {
    favoriteColor: {
        handler: () => Math.random() < 0.75 ? 'purple': 'green'
    }
}

Command Options

handler

This is required for every command. It's a function that runs the command.

noOptions

Set this to true if you would not like your command to accept any options.

format

A Sandhands format to validate that commands arguments. This can be used to ensure all of your arguments are formatted correctly. Each individual argument can be given it's own format, in which case the command might look like this

{
   handler: someFunction,
   args: {
        name: {
            format: String // Gets Angry if the name argument provided is not a string
        }
   }
}

To ensure you received a valid set of primary arguments, you could provide a format that looks something like this

{
    _: [String],
    secondaryOption: Boolean,
    randomOption: Number
}