optimist
Optimist is a node.js library for option parsing for people who hate option parsing. More specifically, this module is for people who like all the --bells and -whistlz of program usage but think optstrings are a waste of time.
With optimist, option parsing doesn't have to suck (as much).
repo | status |
---|---|
substack/node-optimist | |
ttilley/node-optimist |
examples
With Optimist, the options are just a hash! No optstrings attached.
xup.js:
#!/usr/bin/env node
var argv = require('optimist').argv;
if (argv.rif - 5 * argv.xup > 7.138) {
console.log('Buy more riffiwobbles');
}
else {
console.log('Sell the xupptumblers');
}
$ ./xup.js --rif=55 --xup=9.52
Buy more riffiwobbles
$ ./xup.js --rif 12 --xup 8.1
Sell the xupptumblers
But wait! There's more! You can do short options:
short.js:
#!/usr/bin/env node
var argv = require('optimist').argv;
console.log('(%d,%d)', argv.x, argv.y);
$ ./short.js -x 10 -y 21
(10,21)
And booleans, both long and short (and grouped):
bool.js:
#!/usr/bin/env node
var util = require('util');
var argv = require('optimist').argv;
if (argv.s) {
util.print(argv.fr ? 'Le chat dit: ' : 'The cat says: ');
}
console.log(
(argv.fr ? 'miaou' : 'meow') + (argv.p ? '.' : '')
);
$ ./bool.js -s
The cat says: meow
$ ./bool.js -sp
The cat says: meow.
$ ./bool.js -sp --fr
Le chat dit: miaou.
argv._
!
And non-hypenated options too! Just use nonopt.js:
#!/usr/bin/env node
var argv = require('optimist').argv;
console.log('(%d,%d)', argv.x, argv.y);
console.log(argv._);
$ ./nonopt.js -x 6.82 -y 3.35 moo
(6.82,3.35)
[ 'moo' ]
$ ./nonopt.js foo -x 0.54 bar -y 1.12 baz
(0.54,1.12)
[ 'foo', 'bar', 'baz' ]
Plus, Optimist comes with .usage() and .demand()!
divide.js:
#!/usr/bin/env node
var argv = require('optimist')
.usage('Usage: $0 -x [num] -y [num]')
.demand(['x','y'])
.argv;
console.log(argv.x / argv.y);
$ ./divide.js -x 55 -y 11
5
$ node ./divide.js -x 4.91 -z 2.51
Usage: node ./divide.js -x [num] -y [num]
Options:
-x [required]
-y [required]
Missing required arguments: y
EVEN MORE HOLY COW
default_singles.js:
#!/usr/bin/env node
var argv = require('optimist')
.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('optimist')
.default({ x : 10, y : 10 })
.argv
;
console.log(argv.x + argv.y);
$ ./default_hash.js -y 7
17
And if you really want to get all descriptive about it...
boolean_single.js
#!/usr/bin/env node
var argv = require('optimist')
.boolean('v')
.argv
;
console.dir(argv);
$ ./boolean_single.js -v foo bar baz
true
[ 'bar', 'baz', 'foo' ]
boolean_double.js
#!/usr/bin/env node
var argv = require('optimist')
.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' ]
Optimist is here to help...
You can describe parameters for help messages and set aliases. Optimist figures out how to format a handy help string automatically.
line_count.js
#!/usr/bin/env node
var argv = require('optimist')
.usage('Count the lines in a file.\nUsage: $0')
.demand('f')
.alias('f', 'file')
.describe('f', 'Load a file')
.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 the lines in a file.
Usage: node ./line_count.js
Options:
-f, --file Load a file [required]
Missing required arguments: f
$ node line_count.js --file line_count.js
20
$ node line_count.js -f line_count.js
20
methods
By itself,
require('optimist').argv
will use process.argv
array to construct the argv
object.
You can pass in the process.argv
yourself:
require('optimist')([ '-x', '1', '-y', '2' ]).argv
or use .parse() to do the same thing:
require('optimist').parse([ '-x', '1', '-y', '2' ])
The rest of these methods below come in just before the terminating .argv
.
.alias(key, alias)
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.
.default(key, value)
Set argv[key]
to value
if no option was specified on process.argv
.
Optionally .default()
can take an object that maps keys to default values.
.demand(key)
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._
.
If key
is an Array, demand each element.
.describe(key, desc)
Describe a key
for the generated usage information.
Optionally .describe()
can take an object that maps keys to descriptions.
.options(key, opt)
Instead of chaining together .alias().demand().default()
, you can specify
keys in opt
for each of the chainable methods.
For example:
var argv = require('optimist')
.options('f', {
alias : 'file',
default : '/etc/passwd',
})
.argv
;
is the same as
var argv = require('optimist')
.alias('f', 'file')
.default('f', '/etc/passwd')
.argv
;
Optionally .options()
can take an object that maps keys to opt
parameters.
.usage(message)
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.
.check(fn)
Check that certain conditions are met in the provided arguments.
If fn
throws or returns false
, show the thrown error, usage information, and
exit.
.boolean(key)
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
.
If key
never shows up as a flag in process.arguments
, argv[key]
will be
false
.
If key
is an Array, interpret all the elements as booleans.
.string(key)
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.
.wrap(columns)
Format usage output to wrap at columns
many columns.
.help()
Return the generated usage string.
.showHelp(fn=console.error)
Print the usage data using fn
for printing.
.parse(args)
Parse args
instead of process.argv
. Returns the argv
object.
.argv
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.
parsing tricks
stop parsing
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' ],
'$0': 'node ./examples/reflect.js',
a: 1,
b: 2 }
negate fields
If you want to explicity 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
{ _: [],
'$0': 'node ./examples/reflect.js',
a: true,
b: false }
numbers
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.
duplicates
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
{ _: [],
'$0': 'node ./examples/reflect.js',
x: [ 5, 8, 0 ] }
dot notation
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
{ _: [],
'$0': 'node ./examples/reflect.js',
foo: { bar: { baz: 33 }, quux: 5 } }
installation
With npm, just do: npm install optimist
or clone this project on github:
git clone http://github.com/substack/node-optimist.git
To run the tests with expresso, just do:
expresso
inspired By
This module is loosely inspired by Perl's Getopt::Casual.