yargs-unparser

What is yargs-unparser?

The yargs-unparser npm package is used to reverse the process of parsing arguments. It takes an argv object, like the one yargs or minimist would generate, and turns it back into a string of command-line arguments. This can be useful for debugging, logging, or recreating command lines for subprocesses.

What are yargs-unparser's main functionalities?

Unparsing arguments

This feature allows you to take an argument object and convert it back into an array of command-line arguments.

const yargsUnparser = require('yargs-unparser');
const argv = { _: ['run'], 'file': 'test.js', 'verbose': true };
const unparsedArgs = yargsUnparser(argv);
console.log(unparsedArgs); // Output: ['run', '--file=test.js', '--verbose']

Other packages similar to yargs-unparser

minimist

Minimist is a library for parsing command-line arguments. Unlike yargs-unparser, it does not unparse arguments but is commonly used for the initial parsing step that yargs-unparser would reverse.

commander

Commander is a complete solution for node.js command-line interfaces. It is similar to yargs in that it helps with parsing arguments, but it does not have a built-in feature to unparse them like yargs-unparser.

arg

Arg is a simple argument parsing library with a focus on performance. It does not have the unparse functionality but serves a similar initial purpose of parsing command-line arguments.

README

yargs-unparser

Converts back a yargs argv object to its original array form.

Probably the unparser word doesn't even exist, but it sounds nice and goes well with yargs-parser.

The code originally lived in MOXY's GitHub but was later moved here for discoverability.

Installation

$ npm install yargs-unparser

Usage

const parse = require('yargs-parser');
const unparse = require('yargs-unparser');

const argv = parse(['--no-boolean', '--number', '4', '--string', 'foo'], {
    boolean: ['boolean'],
    number: ['number'],
    string: ['string'],
});
// { boolean: false, number: 4, string: 'foo', _: [] }

const unparsedArgv = unparse(argv);
// ['--no-boolean', '--number', '4', '--string', 'foo'];

The second argument of unparse accepts an options object:

• alias: The aliases so that duplicate options aren't generated
• default: The default values so that the options with default values are omitted
• command: The command first argument so that command names and positional arguments are handled correctly

Example with command options

const yargs = require('yargs');
const unparse = require('yargs-unparser');

const argv = yargs
    .command('my-command <positional>', 'My awesome command', (yargs) =>
        yargs
        .option('boolean', { type: 'boolean' })
        .option('number', { type: 'number' })
        .option('string', { type: 'string' })
    )
    .parse(['my-command', 'hello', '--no-boolean', '--number', '4', '--string', 'foo']);
// { positional: 'hello', boolean: false, number: 4, string: 'foo', _: ['my-command'] }

const unparsedArgv = unparse(argv, {
    command: 'my-command <positional>',
});
// ['my-command', 'hello', '--no-boolean', '--number', '4', '--string', 'foo'];

Caveats

The returned array can be parsed again by yargs-parser using the default configuration. If you used custom configuration that you want yargs-unparser to be aware, please fill an issue.

If you coerce in weird ways, things might not work correctly.

Tests

$ npm test
$ npm test -- --watch during development

License

MIT License

Changelog

1.6.1 (2020-06-17)

Bug Fixes

• deps: downgrade yargs, such that we continue supporting Node 6 (#57) (f69406c)