arguments

Parse conventional CLI arguments.

--help and --verbose arguments are included as defaults.

{
	help: {
		shortName: 'h',
		type: Boolean,
	},
	verbose: {
		shortName: 'v',
		type: Boolean,
	},
}

API

import ArgumentParser from '@ryel/arguments';

const argumentsParser = new ArgumentParser(argumentsSpecification, options);

const args = argumentsParser.parse();

argumentsSpecification is an object specifying all expected arguments. The specification must provide a long name for each argument, but all other properties are optional.

By default an argument will be considered a boolean unless a type is provided. Arguments specified with a type of Boolean can either be provided as flags, or can be provided as an argument with a value that is boolean like. Boolean like values include true, t, yes, y and 1 as truthy and false, f, no, n and 0 as falsy. Arguments specified with a type of Number will be parsed from a string to a number.

A short name can be provided by shortName and must be a single character which is unique to all other arguments.

If an argument should always be provided, required can be specified for the argument as true.

A default value can be specified for an argument, to be used in the absence of the argument using defaultValue. By default, boolean arguments are considered to have a defaultValue of false.

If boolean, string and number arguments aren't enough, mapValue can be specified for an argument as a function to transform the argument as required.

options can be an object with the following properties:

helpUsage: string = 'Options:';
helpOnNoArgs: boolean = true;
errorOnUnknownArgs: boolean = true;

helpUsage is a string to be output to the console before listing the usage of all arguments in the specification.

helpOnNoArgs will default to output help and argument usage to the console when no arguments are provided.

errorOnUnknownArgs will default to throwing an error when the parser encounters an argument not provided in the specification.

Using the following example arguments specification:

{
	age: {
		shortName: 'a',
		type: Number,
	},
	fullName: {
		shortName: 'n',
		type: String,
		required: true,
	},
	jobTitle: {
		type: String,
		defaultValue: 'Developer',
	},
	skills: {
		type: String,
		mapValue: (value) => value.split(','),
	},
	special: {
		shortName: 's',
	},
	unplugged: {
		shortName: 'u',
		type: Boolean,
		defaultValue: true,
	},
}

Arguments specified as required must provided, otherwise an error will be thrown. All arguments that are not boolean arguments require a value to be parsed, a value can be provided with the argument name or as the following argument.

> cli --fullName="Thomas A. Anderson"
> cli --fullName "Thomas A. Anderson"

Arguments specified with a shortName such as fullName can be provided in short.

> cli -n="Thomas A. Anderson"
> cli -n "Thomas A. Anderson"

Arguments specified with a defaultValue that is truthy and that are boolean arguments, such as unplugged will be inverted to false when provided.

> cli --fullName="Thomas A. Anderson" -u

Arguments specified with a shortName that are boolean arguments, such as special and verbose, can be concatenated and provided in any order.

> cli --fullName="Thomas A. Anderson" -sv
> cli --fullName="Thomas A. Anderson" -vs

Arguments specified with a mapValue such as skills can be provided and transformed (e.g. to an array ['Budo', 'Krav Maga', 'Wushu']).

> cli --fullName="Thomas A. Anderson" --skills Budo,"Krav Maga",Wushu