Yargs be a node.js library fer hearties tryin' ter parse optstrings.
With yargs, ye be havin' a map that leads straight to yer treasure! Treasure of course, being a simple option hash.
Yargs is the official successor to optimist. Please feel free to submit issues and pull requests. If you'd like to contribute and don't know where to start, have a look at the issue list :)
plunder.js:
#!/usr/bin/env node
var argv = require('yargs').argv;
if (argv.ships > 3 && argv.distance < 53.5) {
console.log('Plunder more riffiwobbles!');
} else {
console.log('Retreat from the xupptumblers!');
}
$ ./plunder.js --ships=4 --distance=22
Plunder more riffiwobbles!
$ ./plunder.js --ships 12 --distance 98.7
Retreat from the xupptumblers!
short.js:
#!/usr/bin/env node
var argv = require('yargs').argv;
console.log('(%d,%d)', argv.x, argv.y);
$ ./short.js -x 10 -y 21
(10,21)
bool.js:
#!/usr/bin/env node
var argv = require('yargs').argv;
if (argv.s) {
process.stdout.write(argv.fr ? 'Le perroquet dit: ' : 'The parrot says: ');
}
console.log(
(argv.fr ? 'couac' : 'squawk') + (argv.p ? '!' : '')
);
$ ./bool.js -s
The parrot says: squawk
$ ./bool.js -sp
The parrot says: squawk!
$ ./bool.js -sp --fr
Le perroquet dit: couac!
nonopt.js:
#!/usr/bin/env node
var argv = require('yargs').argv;
console.log('(%d,%d)', argv.x, argv.y);
console.log(argv._);
$ ./nonopt.js -x 6.82 -y 3.35 rum
(6.82,3.35)
[ 'rum' ]
$ ./nonopt.js "me hearties" -x 0.54 yo -y 1.12 ho
(0.54,1.12)
[ 'me hearties', 'yo', 'ho' ]
count.js:
#!/usr/bin/env node
var argv = require('yargs')
.count('verbose')
.alias('v', 'verbose')
.argv;
VERBOSE_LEVEL = argv.verbose;
function WARN() { VERBOSE_LEVEL >= 0 && console.log.apply(console, arguments); }
function INFO() { VERBOSE_LEVEL >= 1 && console.log.apply(console, arguments); }
function DEBUG() { VERBOSE_LEVEL >= 2 && console.log.apply(console, arguments); }
WARN("Showing only important stuff");
INFO("Showing semi-important stuff too");
DEBUG("Extra chatty mode");
$ node count.js
Showing only important stuff
$ node count.js -v
Showing only important stuff
Showing semi-important stuff too
$ node count.js -vv
Showing only important stuff
Showing semi-important stuff too
Extra chatty mode
$ node count.js -v --verbose
Showing only important stuff
Showing semi-important stuff too
Extra chatty mode
area.js:
#!/usr/bin/env node
var argv = require('yargs')
.usage('Usage: $0 -w [num] -h [num]')
.demand(['w','h'])
.argv;
console.log("The area is:", argv.w * argv.h);
$ ./area.js -w 55 -h 11
The area is: 605
$ node ./area.js -w 4.91 -w 2.51
Usage: area.js -w [num] -h [num]
Options:
-w [required]
-h [required]
Missing required arguments: h
demand_count.js:
#!/usr/bin/env node
var argv = require('yargs')
.demand(2)
.argv;
console.dir(argv);
$ ./demand_count.js a
Not enough non-option arguments: got 1, need at least 2
$ ./demand_count.js a b
{ _: [ 'a', 'b' ], '$0': 'demand_count.js' }
$ ./demand_count.js a b c
{ _: [ 'a', 'b', 'c' ], '$0': 'demand_count.js' }
default_singles.js:
#!/usr/bin/env node
var argv = require('yargs')
.default('x', 10)
.default('y', 10)
.argv
;
console.log(argv.x + argv.y);
$ ./default_singles.js -x 5
15
default_hash.js:
#!/usr/bin/env node
var argv = require('yargs')
.default({ x : 10, y : 10 })
.argv
;
console.log(argv.x + argv.y);
$ ./default_hash.js -y 7
17
boolean_single.js:
#!/usr/bin/env node
var argv = require('yargs')
.boolean('v')
.argv
;
console.dir(argv.v);
console.dir(argv._);
$ ./boolean_single.js -v "me hearties" yo ho
true
[ 'me hearties', 'yo', 'ho' ]
boolean_double.js:
#!/usr/bin/env node
var argv = require('yargs')
.boolean(['x','y','z'])
.argv
;
console.dir([ argv.x, argv.y, argv.z ]);
console.dir(argv._);
$ ./boolean_double.js -x -z one two three
[ true, false, true ]
[ 'one', 'two', 'three' ]
Ye can describe parameters fer help messages and set aliases. Yargs figures out how ter format a handy help string automatically.
line_count.js:
#!/usr/bin/env node
var argv = require('yargs')
.usage('Usage: $0 <command> [options]')
.command('count', 'Count the lines in a file')
.demand(1)
.example('$0 count -f foo.js', 'count the lines in the given file')
.demand('f')
.alias('f', 'file')
.nargs('f', 1)
.describe('f', 'Load a file')
.help('h')
.alias('h', 'help')
.epilog('copyright 2015')
.argv;
var fs = require('fs');
var s = fs.createReadStream(argv.file);
var lines = 0;
s.on('data', function (buf) {
lines += buf.toString().match(/\n/g).length;
});
s.on('end', function () {
console.log(lines);
});
$ node line_count.js count
Usage: line_count.js <command> [options]
Commands:
count Count the lines in a file
Options:
-f, --file Load a file [required]
-h, --help Show help [boolean]
Examples:
line_count.js count -f foo.js count the lines in the given file
copyright 2015
Missing required arguments: f
$ node line_count.js count --file line_count.js
26
$ node line_count.js count -f line_count.js
26
By itself,
require('yargs').argv
will use the process.argv
array to construct the argv
object.
You can pass in the process.argv
yourself:
require('yargs')([ '-x', '1', '-y', '2' ]).argv
or use .parse()
to do the same thing:
require('yargs').parse([ '-x', '1', '-y', '2' ])
The rest of these methods below come in just before the terminating .argv
.
Set key names as equivalent such that updates to a key will propagate to aliases and vice-versa.
Optionally .alias()
can take an object that maps keys to aliases.
Each key of this object should be the canonical version of the option, and each
value should be a string or an array of strings.
Get the arguments as a plain old object.
Arguments without a corresponding flag show up in the argv._
array.
The script name or node command is available at argv.$0
similarly to how $0
works in bash or perl.
If yargs
is executed in an environment that embeds node and there's no script name (e.g.
Electron or nw.js), it will ignore the first parameter since it
expects it to be the script name. In order to override this behavior, use .parse(process.argv.slice(1))
instead of .argv
and the first parameter won't be ignored.
Tell the parser to interpret key
as an array. If .array('foo')
is set,
--foo foo bar
will be parsed as ['foo', 'bar']
rather than as 'foo'
.
Interpret key
as a boolean. If a non-flag option follows key
in
process.argv
, that string won't get set as the value of key
.
key
will default to false
, unless a default(key, undefined)
is
explicitly set.
If key
is an array, interpret all the elements as booleans.
Check that certain conditions are met in the provided arguments.
fn
is called with two arguments, the parsed argv
hash and an array of options and their aliases.
If fn
throws or returns a non-truthy value, show the thrown error, usage information, and
exit.
Limit valid values for key
to a predefined set of choices
, given as an array
or as an individual value.
var argv = require('yargs')
.alias('i', 'ingredient')
.describe('i', 'choose your sandwich ingredients')
.choices('i', ['peanut-butter', 'jelly', 'banana', 'pickles'])
.help('help')
.argv
If this method is called multiple times, all enumerated values will be merged together. Choices are generally strings or numbers, and value matching is case-sensitive.
Optionally .choices()
can take an object that maps multiple keys to their
choices.
Choices can also be specified as choices
in the object given to option()
.
var argv = require('yargs')
.option('size', {
alias: 's',
describe: 'choose a size',
choices: ['xs', 's', 'm', 'l', 'xl']
})
.argv
Document the commands exposed by your application.
Use desc
to provide a description for each command your application accepts (the
values stored in argv._
). Set desc
to false
to create a hidden command.
Hidden commands don't show up in the help output and aren't available for
completion.
Optionally, you can provide a builder
object to give hints about the
options that your command accepts:
yargs.command('get', 'make a get HTTP request', {
url: {
alias: 'u',
default: 'http://yargs.js.org/'
}
})
.help()
.argv
builder
can also be a function. This function is executed
with a yargs
instance, and can be used to provide advanced command specific help:
yargs.command('get', 'make a get HTTP request', function (yargs) {
return yargs.option('url', {
alias: 'u',
default: 'http://yargs.js.org/'
})
})
.help()
.argv
You can also provide a handler function, which will be executed with the
parsed argv
object:
yargs
.command(
'get',
'make a get HTTP request',
function (yargs) {
return yargs.option('u', {
alias: 'url',
describe: 'the URL to make an HTTP request to'
})
},
function (argv) {
console.log(argv.url)
}
)
.help()
.argv
Commands can accept optional and required positional arguments. Required
positional arguments take the form <foo>
, and optional arguments
take the form [bar]
. The parsed positional arguments will be populated in
argv
:
yargs.command('get <source> [proxy]', 'make a get HTTP request')
.help()
.argv
The last positional argument can optionally accept an array of
values, by using the ..
operator:
yargs.command('download <url> [files..]', 'download several files')
.help()
.argv
For complicated commands you can pull the logic into a module. A module simply needs to export:
exports.command
: string that executes this command when given on the command line, may contain positional argsexports.describe
: string used as the description for the command in help text, usefalse
for a hidden commandexports.builder
: object declaring the options the command accepts, or a function accepting and returning a yargs instanceexports.handler
: a function which will be passed the parsed argv.
// my-module.js
exports.command = 'get <source> [proxy]'
exports.describe = 'make a get HTTP request'
exports.builder = {
banana: {
default: 'cool'
},
batman: {
default: 'sad'
}
}
exports.handler = function (argv) {
// do something with argv.
}
You then register the module like so:
yargs.command(require('my-module'))
.help()
.argv
Or if the module does not export command
and describe
(or if you just want to override them):
yargs.command('get <source> [proxy]', 'make a get HTTP request', require('my-module'))
.help()
.argv
Enable bash-completion shortcuts for commands and options.
cmd
: When present in argv._
, will result in the .bashrc
completion script
being outputted. To enable bash completions, concat the generated script to your
.bashrc
or .bash_profile
.
description
: Provide a description in your usage instructions for the command
that generates bash completion scripts.
fn
: Rather than relying on yargs' default completion functionality, which
shiver me timbers is pretty awesome, you can provide your own completion
method.
If invoked without parameters, .completion()
will make completion
the command to output
the completion script.
var argv = require('yargs')
.completion('completion', function(current, argv) {
// 'current' is the current command being completed.
// 'argv' is the parsed arguments so far.
// simply return an array of completions.
return [
'foo',
'bar'
];
})
.argv;
You can also provide asynchronous completions.
var argv = require('yargs')
.completion('completion', function(current, argv, done) {
setTimeout(function() {
done([
'apple',
'banana'
]);
}, 500);
})
.argv;
But wait, there's more! You can return an asynchronous promise.
var argv = require('yargs')
.completion('completion', function(current, argv, done) {
return new Promise(function (resolve, reject) {
setTimeout(function () {
resolve(['apple', 'banana'])
}, 10)
})
})
.argv;
Tells the parser that if the option specified by key
is passed in, it
should be interpreted as a path to a JSON config file. The file is loaded
and parsed, and its properties are set as arguments.
If invoked without parameters, .config()
will make --config
the option to pass the JSON config file.
An optional description
can be provided to customize the config (key
) option
in the usage string.
An optional parseFn
can be used to provide a custom parser. The parsing
function must be synchronous, and should return an object containing
key value pairs or an error.
var argv = require('yargs')
.config('settings', function (configPath) {
return JSON.parse(fs.readFileSync(configPath, 'utf-8'))
})
.argv
You can also pass an explicit configuration object
, it will be parsed
and its properties will be set as arguments.
var argv = require('yargs')
.config({foo: 1, bar: 2})
.argv
console.log(argv)
$ node test.js
{ _: [],
foo: 1,
bar: 2,
'$0': 'test.js' }
Interpret key
as a boolean flag, but set its parsed value to the number of
flag occurrences rather than true
or false
. Default value is thus 0
.
Note: The .defaults()
alias is deprecated. It will be
removed in the next major version.
Set argv[key]
to value
if no option was specified in process.argv
.
Optionally .default()
can take an object that maps keys to default values.
But wait, there's more! The default value can be a function
which returns
a value. The name of the function will be used in the usage string:
var argv = require('yargs')
.default('random', function randomValue() {
return Math.random() * 256;
}).argv;
Optionally, description
can also be provided and will take precedence over
displaying the value in the usage instructions:
.default('timeout', 60000, '(one-minute)')
If key
is a string, show the usage information and exit if key
wasn't
specified in process.argv
.
If key
is a number, demand at least as many non-option arguments, which show
up in argv._
. A second number can also optionally be provided, which indicates
the maximum number of non-option arguments.
If key
is an array, demand each element.
If a msg
string is given, it will be printed when the argument is missing,
instead of the standard error message. This is especially helpful for the non-option arguments in argv._
.
If a boolean
value is given, it controls whether the option is demanded;
this is useful when using .options()
to specify command line parameters.
A combination of .demand(1)
and .strict()
will allow you to require a user to pass at least one command:
var argv = require('yargs')
.command('install', 'tis a mighty fine package to install')
.demand(1)
.strict()
.argv
Similarly, you can require a command and arguments at the same time:
var argv = require('yargs')
.command('install', 'tis a mighty fine package to install')
.demand(1, ['w', 'm'])
.strict()
.argv
Describe a key
for the generated usage information.
Optionally .describe()
can take an object that maps keys to descriptions.
Should yargs attempt to detect the os' locale? Defaults to true
.
Tell yargs to parse environment variables matching the given prefix and apply them to argv as though they were command line arguments.
Use the "__" separator in the environment variable to indicate nested options. (e.g. prefix_nested__foo => nested.foo)
If this method is called with no argument or with an empty string or with true
,
then all env vars will be applied to argv.
Program arguments are defined in this order of precedence:
- Command line args
- Config file
- Env var
- Configured defaults
var argv = require('yargs')
.env('MY_PROGRAM')
.option('f', {
alias: 'fruit-thing',
default: 'apple'
})
.argv
console.log(argv)
$ node fruity.js
{ _: [],
f: 'apple',
'fruit-thing': 'apple',
fruitThing: 'apple',
'$0': 'fruity.js' }
$ MY_PROGRAM_FRUIT_THING=banana node fruity.js
{ _: [],
fruitThing: 'banana',
f: 'banana',
'fruit-thing': 'banana',
'$0': 'fruity.js' }
$ MY_PROGRAM_FRUIT_THING=banana node fruity.js -f cat
{ _: [],
f: 'cat',
'fruit-thing': 'cat',
fruitThing: 'cat',
'$0': 'fruity.js' }
Env var parsing is disabled by default, but you can also explicitly disable it
by calling .env(false)
, e.g. if you need to undo previous configuration.
A message to print at the end of the usage instructions, e.g.
var argv = require('yargs')
.epilogue('for more information, find our manual at http://example.com');
Give some example invocations of your program. Inside cmd
, the string
$0
will get interpolated to the current script name or node command for the
present script similar to how $0
works in bash or perl.
Examples will be printed out as part of the help message.
By default, yargs exits the process when the user passes a help flag, uses the
.version
functionality, or when validation fails. Calling
.exitProcess(false)
disables this behavior, enabling further actions after
yargs have been validated.
Method to execute when a failure occurs, rather than printing the failure message.
fn
is called with the failure message that would have been printed and the
Error
instance originally thrown, if any.
var argv = require('yargs')
.fail(function (msg, err) {
if (err) throw err // preserve stack
console.error('You broke it!')
console.error(msg)
process.exit(1)
})
.argv
Allows to programmatically get completion choices for any line.
args
: An array of the words in the command line to complete.
done
: The callback to be called with the resulting completions.
For example:
require('yargs')
.option('foobar', {})
.option('foobaz', {})
.completion()
.getCompletion(['./test.js', '--foo'], function (completions) {
console.log(completions)
})
Outputs the same completion choices as ./test.js --foo
TAB: --foobar
and --foobaz
Indicate that an option (or group of options) should not be reset when a command is executed, as an example:
var argv = require('yargs')
.option('a', {
alias: 'all',
default: true
})
.option('n', {
alias: 'none',
default: true
})
.command('foo', 'foo command', function (yargs) {
return yargs.option('b', {
alias: 'bar'
})
})
.help('help')
.global('a')
.argv
If the foo
command is executed the all
option will remain, but the none
option will have been eliminated.
help
, version
, and completion
options default to being global.
Given a key, or an array of keys, places options under an alternative heading when displaying usage instructions, e.g.,
var yargs = require('yargs')(['--help'])
.help()
.group('batman', 'Heroes:')
.describe('batman', "world's greatest detective")
.wrap(null)
.argv
Heroes:
--batman world's greatest detective
Options:
--help Show help [boolean]
Add an option (e.g. --help
) that displays the usage string and exits the
process. If present, the description
parameter customizes the description of
the help option in the usage string.
If invoked without parameters, .help()
will make --help
the option to trigger
help output.
Example:
var yargs = require("yargs")(['--help'])
.usage("$0 -operand1 number -operand2 number -operation [add|subtract]")
.help()
.argv
Later on, argv
can be retrieved with yargs.argv
.
Given the key x
is set, it is required that the key y
is set.
Optionally .implies()
can accept an object specifying multiple implications.
Return the locale that yargs is currently using.
By default, yargs will auto-detect the operating system's locale so that yargs-generated help content will display in the user's language.
To override this behavior with a static locale, pass the desired locale as a string to this method (see below).
Override the auto-detected locale from the user's operating system with a static
locale. Note that the OS locale can be modified by setting/exporting the LC_ALL
environment variable.
var argv = require('yargs')
.usage('./$0 - follow ye instructions true')
.option('option', {
alias: 'o',
describe: "'tis a mighty fine option",
demand: true
})
.command('run', "Arrr, ya best be knowin' what yer doin'")
.example('$0 run foo', "shiver me timbers, here's an example for ye")
.help('help')
.wrap(70)
.locale('pirate')
.argv
./test.js - follow ye instructions true
Choose yer command:
run Arrr, ya best be knowin' what yer doin'
Options for me hearties!
--option, -o 'tis a mighty fine option [requi-yar-ed]
--help Parlay this here code of conduct [boolean]
Ex. marks the spot:
test.js run foo shiver me timbers, here's an example for ye
Ye be havin' to set the followin' argument land lubber: option
Locales currently supported:
- de: German.
- en: American English.
- es: Spanish.
- fr: French.
- id: Indonesian.
- it: Italian.
- ja: Japanese.
- ko: Korean.
- nb: Norwegian Bokmรฅl.
- pirate: American Pirate.
- pl: Polish.
- pt: Portuguese.
- pt_BR: Brazilian Portuguese.
- tr: Turkish.
- zh: Chinese.
To submit a new translation for yargs:
- use
./locales/en.json
as a starting point. - submit a pull request with the new locale file.
The Microsoft Terminology Search can be useful for finding the correct terminology in your locale.
The number of arguments that should be consumed after a key. This can be a useful hint to prevent parsing ambiguity. For example:
var argv = require('yargs')
.nargs('token', 1)
.parse(['--token', '-my-token']);
parses as:
{ _: [], token: '-my-token', '$0': 'node test' }
Optionally .nargs()
can take an object of key
/narg
pairs.
The key provided represents a path and should have path.normalize()
applied.
Tell the parser to always interpret key
as a number.
If key
is an array, all elements will be parsed as numbers.
If the option is given on the command line without a value, argv
will be
populated with undefined
.
If the value given on the command line cannot be parsed as a number, argv
will
be populated with NaN
.
Note that decimals, hexadecimals, and scientific notation are all accepted.
var argv = require('yargs')
.number('n')
.number(['width', 'height'])
.argv
Instead of chaining together .alias().demand().default().describe().string()
, you can specify
keys in opt
for each of the chainable methods.
For example:
var argv = require('yargs')
.option('f', {
alias: 'file',
demand: true,
default: '/etc/passwd',
describe: 'x marks the spot',
type: 'string'
})
.argv
;
is the same as
var argv = require('yargs')
.alias('f', 'file')
.demand('f')
.default('f', '/etc/passwd')
.describe('f', 'x marks the spot')
.string('f')
.argv
;
Optionally .options()
can take an object that maps keys to opt
parameters.
var argv = require('yargs')
.options({
'f': {
alias: 'file',
demand: true,
default: '/etc/passwd',
describe: 'x marks the spot',
type: 'string'
}
})
.argv
;
Valid opt
keys include:
alias
: string or array of strings, alias(es) for the canonical option key, seealias()
array
: boolean, interpret option as an array, seearray()
boolean
: boolean, interpret option as a boolean flag, seeboolean()
choices
: value or array of values, limit valid option arguments to a predefined set, seechoices()
config
: boolean, interpret option as a path to a JSON config file, seeconfig()
configParser
: function, provide a custom config parsing function, seeconfig()
count
: boolean, interpret option as a count of boolean flags, seecount()
default
: value, set a default value for the option, seedefault()
defaultDescription
: string, use this description for the default value in help content, seedefault()
demand
/require
/required
: boolean or string, demand the option be given, with optional error message, seedemand()
desc
/describe
/description
: string, the option description for help content, seedescribe()
global
: boolean, indicate that this key should not be reset when a command is invoked, seeglobal()
group
: string, when displaying usage instructions place the option under an alternative group heading, seegroup()
nargs
: number, specify how many arguments should be consumed for the option, seenargs()
normalize
: boolean, applypath.normalize()
to the option, seenormalize()
number
: boolean, interpret option as a number,number()
requiresArg
: boolean, require the option be specified with a value, seerequiresArg()
skipValidation
: boolean, skips validation if the option is present, seeskipValidation()
string
: boolean, interpret option as a string, seestring()
type
: one of the following strings
Parse args
instead of process.argv
. Returns the argv
object.
args
may either be a pre-processed argv array, or a raw argument string.
Similar to config()
, indicates that yargs should interpret the object from the specified key in package.json
as a configuration object.
cwd
can optionally be provided, the package.json will be read
from this location.
An alias for demand()
. See docs there.
Specifies either a single option key (string), or an array of options that must be followed by option values. If any option value is missing, show the usage information and exit.
The default behavior is to set the value of any key not followed by an
option value to true
.
Reset the argument object built up so far. This is useful for creating nested command line interfaces. Use global to specify keys that should not be reset.
var yargs = require('yargs')
.usage('$0 command')
.command('hello', 'hello command')
.command('world', 'world command')
.demand(1, 'must provide a valid command'),
argv = yargs.argv,
command = argv._[0];
if (command === 'hello') {
yargs.reset()
.usage('$0 hello')
.help('h')
.example('$0 hello', 'print the hello message!')
.argv
console.log('hello!');
} else if (command === 'world'){
yargs.reset()
.usage('$0 world')
.help('h')
.example('$0 world', 'print the world message!')
.argv
console.log('world!');
} else {
yargs.showHelp();
}
Generate a bash completion script. Users of your application can install this
script in their .bashrc
, and yargs will provide completion shortcuts for
commands and options.
Print the usage data using the console
function consoleLevel
for printing.
Example:
var yargs = require("yargs")
.usage("$0 -operand1 number -operand2 number -operation [add|subtract]");
yargs.showHelp(); //prints to stderr using console.error()
Or, to print the usage data to stdout
instead, you can specify the use of console.log
:
yargs.showHelp("log"); //prints to stdout using console.log()
Later on, argv
can be retrieved with yargs.argv
.
By default, yargs outputs a usage string if any error is detected. Use the
.showHelpOnFail()
method to customize this behavior. If enable
is false
,
the usage string is not output. If the message
parameter is present, this
message is output after the error message.
line_count.js:
#!/usr/bin/env node
var argv = require('yargs')
.usage('Count the lines in a file.\nUsage: $0 -f <file>')
.demand('f')
.alias('f', 'file')
.describe('f', 'Load a file')
.string('f')
.showHelpOnFail(false, 'Specify --help for available options')
.help('help')
.argv;
// etc.
$ node line_count.js
Missing argument value: f
Specify --help for available options
Specifies either a single option key (string), or an array of options. If any of the options is present, yargs validation is skipped.
Any command-line argument given that is not demanded, or does not have a corresponding description, will be reported as an error.
Tell the parser logic not to interpret key
as a number or boolean.
This can be useful if you need to preserve leading zeros in an input.
If key
is an array, interpret all the elements as strings.
.string('_')
will result in non-hyphenated arguments being interpreted as strings,
regardless of whether they resemble numbers.
Override the default strings used by yargs with the key/value
pairs provided in obj
:
var argv = require('yargs')
.command('run', 'the run command')
.help('help')
.updateStrings({
'Commands:': 'My Commands -->\n'
})
.wrap(null)
.argv
My Commands -->
run the run command
Options:
--help Show help [boolean]
If you explicitly specify a locale()
, you should do so before calling
updateStrings()
.
Set a usage message to show which commands to use. Inside message
, the string
$0
will get interpolated to the current script name or node command for the
present script similar to how $0
works in bash or perl.
opts
is optional and acts like calling .options(opts)
.
Add an option (e.g. --version
) that displays the version number (given by the
version
parameter) and exits the process.
If no arguments are passed to version
(.version()
), yargs will parse the package.json
of your module and use its version
value. The default value of option
is --version
.
You can provide a function
for version, rather than a string.
This is useful if you want to use a version stored in a location other than package.json:
var argv = require('yargs')
.version(function() {
return require('../lib/version').version;
})
.argv;
Format usage output to wrap at columns
many columns.
By default wrap will be set to Math.min(80, windowWidth)
. Use .wrap(null)
to
specify no column limit (no right-align). Use .wrap(yargs.terminalWidth())
to
maximize the width of yargs' usage instructions.
Use --
to stop parsing flags and stuff the remainder into argv._
.
$ node examples/reflect.js -a 1 -b 2 -- -c 3 -d 4
{ _: [ '-c', '3', '-d', '4' ],
a: 1,
b: 2,
'$0': 'examples/reflect.js' }
If you want to explicitly set a field to false instead of just leaving it
undefined or to override a default you can do --no-key
.
$ node examples/reflect.js -a --no-b
{ _: [], a: true, b: false, '$0': 'examples/reflect.js' }
Every argument that looks like a number (!isNaN(Number(arg))
) is converted to
one. This way you can just net.createConnection(argv.port)
and you can add
numbers out of argv
with +
without having that mean concatenation,
which is super frustrating.
If you specify a flag multiple times it will get turned into an array containing all the values in order.
$ node examples/reflect.js -x 5 -x 8 -x 0
{ _: [], x: [ 5, 8, 0 ], '$0': 'examples/reflect.js' }
When you use dots (.
s) in argument names, an implicit object path is assumed.
This lets you organize arguments into nested objects.
$ node examples/reflect.js --foo.bar.baz=33 --foo.quux=5
{ _: [],
foo: { bar: { baz: 33 }, quux: 5 },
'$0': 'examples/reflect.js' }
Short numeric -n5
style arguments work too:
$ node examples/reflect.js -n123 -m456
{ _: [], n: 123, m: 456, '$0': 'examples/reflect.js' }
With npm, just do:
npm install yargs
or clone this project on github:
git clone http://github.com/yargs/yargs.git
To run the tests with npm, just do:
npm test
Using the yargs
stanza in your package.json
you can turn on and off
some of yargs' parsing features:
{
"yargs": {
"short-option-groups": true,
"camel-case-expansion": true,
"dot-notation": true,
"parse-numbers": true,
"boolean-negation": true
}
}
See the yargs-parser module for detailed documentation of this feature.
This module is loosely inspired by Perl's Getopt::Casual.