vardict

Get a dictionary consisting of CLI arguments, parsed and statically typed.

What does it do?

Sometimes, a Node.js program needs to receive arguments from the CLI, like this:

node index.js usa hamburger react

If there is a large number of arguments, they can be annotated in a getopt-ish fashion, like this:

node index.js -country usa -food hamburger -library react

vardict parses the arguments passed on to CLI and makes a dictionary/map object that can be used elsewhere in the program. For the previous example, it would work like this:

{ country: 'usa', food: 'hamburger', library: 'react' }

Rules of parsing

As mentioniod above, the rule of parsing is "getopt-ish", meaning that this package does not work in the exact same way as getopt does.

• Annotations with double hyphens or quotation marks are treated as single entities.
  • node index.js -name Noyan --home Narayanganj will produce { name: 'Noyan', home: 'Narayanganj' }
• Whitespaces and equal signs ('=') are treated as a separator between the annotation and the value.
  • node index.js --state NSW --capital=Sydney will generate { state: 'NSW', capital: 'Sydney' }
• Static typing is enforced on the values, based on the literal inputs. For example, true/false is boolean, and numeric values are number.
  • node index.js -country BD -popDensPerSqKM 1116 -overPop true will yield { country: 'BD', popDensPerSqKM: 1116, overPop: true }
• If there is no value provided after an annotation, it is considered a boolean value and set to true.
  • node index.js -country NZ -covidFree -pop 4886000 -neighbour will output { country: 'NZ', covidFree: true, pop: 4886000, neighbour: true }.
• If the same key is supplied twice, they are merged into an array.
  • node index.js -country Australia -easternStates QLD -easternStates NSW -easternStates VIC -easternStates TAS will give { country: 'Australia', easternStates: ['QLD', 'NSW', 'VIC', 'TAS'] }.
  • node index.js -asl 28 -asl false -asl Sydney will generate { asl: [28, false, 'Sydney'] }.
• If a key is followed by multiple properties, they are merged into an array.
  • node index.js -asl 28 false Sydney will produce { asl: [28, false, 'Sydney'] }, the same as the previous example.

Installation

Add the package via command line.

NPM	Yarn	PNPM	Bun
npm i vardict	yarn add vardict	pnpm add vardict	bun add vardict

How to use

Just import and use the object:

// script.js
import vardict from 'vardict' // ES6
const { default: vardict } = require('vardict') // CommonJS

console.log(vardict)

Here are the input and the output of the code.

node script.js                    \
  --'full name' 'Anirudha Paul'   \
  --age 25                        \
  --single                        \
  -c 'Samsung R&D'                \
  --home Mymensingh               \
  --coolWithLadies false          \
  -wantsToGoTo=USA                \
  --IELTS=7.5                     \
  --favoriteFood kachchi          \
  -nick-name Prasun

{
  'full name': 'Anirudha Paul',
  age: 25,
  single: true,
  c: 'Samsung R&D',
  home: 'Mymensingh',
  coolWithLadies: false,
  wantsToGoTo: 'USA',
  IELTS: 7.5,
  favoriteFood: 'kachchi',
  'nick-name': 'Prasun'
}