@pkgjs/parseargs

parseArgs

🚨 THIS REPO IS AN EARLY WIP -- DO NOT USE ... yet 🚨

Polyfill of future proposal to the nodejs/tooling repo for util.parseArgs()

Scope

It is already possible to build great arg parsing modules on top of what Node.js provides; the prickly API is abstracted away by these modules. Thus, process.parseArgs() is not necessarily intended for library authors; it is intended for developers of simple CLI tools, ad-hoc scripts, deployed Node.js applications, and learning materials.

It is exceedingly difficult to provide an API which would both be friendly to these Node.js users while being extensible enough for libraries to build upon. We chose to prioritize these use cases because these are currently not well-served by Node.js' API.

Links & Resources

• Initial Tooling Issue
• Initial Proposal

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Table of Contents

• 🚀 Getting Started
• 🙌 Contributing
• 💡 process.mainArgs Proposal
  • Implementation:
• 💡 util.parseArgs([config]) Proposal
• 📃 Examples
  • F.A.Qs

---

🚀 Getting Started

1. Install dependencies.

   npm install
   

2. Open the index.js file and start editing!

3. Test your code by calling parseArgs through our test file

   npm test
   

---

🙌 Contributing

Any person who wants to contribute to the initiative is welcome! Please first read the Contributing Guide

Additionally, reading the Examples w/ Output section of this document will be the best way to familiarize yourself with the target expected behavior for parseArgs() once it is fully implemented.

This package was implemented using tape as its test harness.

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💡 process.mainArgs Proposal

Note: This can be moved forward independently of the util.parseArgs() proposal/work.

Implementation:

process.mainArgs = process.argv.slice(process._exec ? 1 : 2)

---

💡 util.parseArgs([config]) Proposal

• config {Object} (Optional) The config parameter is an object supporting the following properties:
  • args {string[]} (Optional) Array of argument strings; defaults to process.mainArgs
  • options {Object} (Optional) An object describing the known options to look for in args; options keys are the long names of the known options, and the values are objects with the following properties:
    • type {'string'|'boolean'} (Optional) Type of known option; defaults to 'boolean';
    • multiple {boolean} (Optional) If true, when appearing one or more times in args, results are collected in an Array
    • short {string} (Optional) A single character alias for an option; When appearing one or more times in args; Respects the multiple configuration
  • strict {Boolean} (Optional) A Boolean on wheather or not to throw an error when unknown args are encountered
• Returns: {Object} An object having properties:
  • flags {Object}, having properties and Boolean values corresponding to parsed options passed
  • values {Object}, have properties and String values corresponding to parsed options passed
  • positionals {string[]}, containing [Positionals][]

---

📃 Examples

const { parseArgs } = require('@pkgjs/parseargs');

// unconfigured
const { parseArgs } = require('@pkgjs/parseargs');
const args = ['-f', '--foo=a', '--bar', 'b'];
const options = {};
const { flags, values, positionals } = parseArgs({ args, options });
// flags = { f: true, bar: true }
// values = { foo: 'a' }
// positionals = ['b']

const { parseArgs } = require('@pkgjs/parseargs');
// withValue
const args = ['-f', '--foo=a', '--bar', 'b'];
const options = {
  foo: {
    type: 'string',
  },
};
const { flags, values, positionals } = parseArgs({ args, options });
// flags = { f: true }
// values = { foo: 'a', bar: 'b' }
// positionals = []

const { parseArgs } = require('@pkgjs/parseargs');
// withValue & multiple
const args = ['-f', '--foo=a', '--foo', 'b'];
const options = {
  foo: {
    type: 'string',
    multiple: true,
  },
};
const { flags, values, positionals } = parseArgs({ args, options });
// flags = { f: true }
// values = { foo: ['a', 'b'] }
// positionals = []

const { parseArgs } = require('@pkgjs/parseargs');
// shorts
const args = ['-f', 'b'];
const options = {
  foo: {
    short: 'f',
  },
};
const { flags, values, positionals } = parseArgs({ args, options });
// flags = { foo: true }
// values = {}
// positionals = ['b']

F.A.Qs

• Is cmd --foo=bar baz the same as cmd baz --foo=bar?
  • yes
• Does the parser execute a function?
  • no
• Does the parser execute one of several functions, depending on input?
  • no
• Can subcommands take options that are distinct from the main command?
  • no
• Does it output generated help when no options match?
  • no
• Does it generated short usage? Like: usage: ls [-ABCFGHLOPRSTUWabcdefghiklmnopqrstuwx1] [file ...]
  • no (no usage/help at all)
• Does the user provide the long usage text? For each option? For the whole command?
  • no
• Do subcommands (if implemented) have their own usage output?
  • no
• Does usage print if the user runs cmd --help?
  • no
• Does it set process.exitCode?
  • no
• Does usage print to stderr or stdout?
  • N/A
• Does it check types? (Say, specify that an option is a boolean, number, etc.)
  • no
• Can an option have more than one type? (string or false, for example)
  • no
• Can the user define a type? (Say, type: path to call path.resolve() on the argument.)
  • no
• Does a --foo=0o22 mean 0, 22, 18, or "0o22"?
  • "0o22"
• Does it coerce types?
  • no
• Does --no-foo coerce to --foo=false? For all flags? Only boolean flags?
  • no, it sets {args:{'no-foo': true}}
• Is --foo the same as --foo=true? Only for known booleans? Only at the end?
  • no, --foo is the same as --foo=
• Does it read environment variables? Ie, is FOO=1 cmd the same as cmd --foo=1?
  • no
• Do unknown arguments raise an error? Are they parsed? Are they treated as positional arguments?
  • no, they are parsed, not treated as positionals
• Does -- signal the end of flags/options?
  • open question
  • If -- signals the end, is -- included as a positional? is program -- foo the same as program foo? Are both {positionals:['foo']}, or is the first one {positionals:['--', 'foo']}?
• Does the API specify whether a -- was present/relevant?
  • no
• Is -bar the same as --bar?
  • no, -bar is a short option or options, with expansion logic that follows the Utility Syntax Guidelines in POSIX.1-2017. -bar expands to -b, -a, -r.
• Is ---foo the same as --foo?
  • no
  • the first flag would be parsed as '-foo'
  • the second flag would be parsed as 'foo'
• Is - a positional? ie, bash some-test.sh | tap -
  • yes

Changelog

0.4.0 (2022-03-12)

⚠ BREAKING CHANGES

• parsing, revisit short option groups, add support for combined short and value (#75)
• restructure configuration to take options bag (#63)

Code Refactoring

• parsing, revisit short option groups, add support for combined short and value (#75) (a92600f)
• restructure configuration to take options bag (#63) (b412095)