1 If you want to write an option parser, and have it be good, there are
2 two ways to do it. The Right Way, and the Wrong Way.
4 The Wrong Way is to sit down and write an option parser. We've all done
7 The Right Way is to write some complex configurable program with so many
8 options that you hit the limit of your frustration just trying to
9 manage them all, and defer it with duct-tape solutions until you see
10 exactly to the core of the problem, and finally snap and write an
11 awesome option parser.
13 If you want to write an option parser, don't write an option parser.
14 Write a package manager, or a source control system, or a service
15 restarter, or an operating system. You probably won't end up with a
16 good one of those, but if you don't give up, and you are relentless and
17 diligent enough in your procrastination, you may just end up with a very
24 var nopt = require("nopt")
25 , Stream = require("stream").Stream
26 , path = require("path")
27 , knownOpts = { "foo" : [String, null]
28 , "bar" : [Stream, Number]
30 , "bloo" : [ "big", "medium", "small" ]
33 , "many1" : [String, Array]
34 , "many2" : [path, Array]
36 , shortHands = { "foofoo" : ["--foo", "Mr. Foo"]
37 , "b7" : ["--bar", "7"]
38 , "m" : ["--bloo", "medium"]
42 // everything is optional.
43 // knownOpts and shorthands default to {}
44 // arg list defaults to process.argv
45 // slice defaults to 2
46 , parsed = nopt(knownOpts, shortHands, process.argv, 2)
50 This would give you support for any of the following:
53 $ node my-program.js --foo "blerp" --no-flag
54 { "foo" : "blerp", "flag" : false }
56 $ node my-program.js ---bar 7 --foo "Mr. Hand" --flag
57 { bar: 7, foo: "Mr. Hand", flag: true }
59 $ node my-program.js --foo "blerp" -f -----p
60 { foo: "blerp", flag: true, pick: true }
62 $ node my-program.js -fp --foofoo
63 { foo: "Mr. Foo", flag: true, pick: true }
65 $ node my-program.js --foofoo -- -fp # -- stops the flag parsing.
66 { foo: "Mr. Foo", argv: { remain: ["-fp"] } }
68 $ node my-program.js --blatzk -fp # unknown opts are ok.
69 { blatzk: true, flag: true, pick: true }
71 $ node my-program.js --blatzk=1000 -fp # but you need to use = if they have a value
72 { blatzk: 1000, flag: true, pick: true }
74 $ node my-program.js --no-blatzk -fp # unless they start with "no-"
75 { blatzk: false, flag: true, pick: true }
77 $ node my-program.js --baz b/a/z # known paths are resolved.
78 { baz: "/Users/isaacs/b/a/z" }
80 # if Array is one of the types, then it can take many
81 # values, and will always be an array. The other types provided
82 # specify what types are allowed in the list.
84 $ node my-program.js --many1 5 --many1 null --many1 foo
85 { many1: ["5", "null", "foo"] }
87 $ node my-program.js --many2 foo --many2 bar
88 { many2: ["/path/to/foo", "path/to/bar"] }
91 Read the tests at the bottom of `lib/nopt.js` for more examples of
92 what this puppy can do.
96 The following types are supported, and defined on `nopt.typeDefs`
98 * String: A normal string. No parsing is done.
99 * path: A file system path. Gets resolved against cwd if not absolute.
100 * url: A url. If it doesn't parse, it isn't accepted.
101 * Number: Must be numeric.
102 * Date: Must parse as a date. If it does, and `Date` is one of the options,
103 then it will return a Date object, not a string.
104 * Boolean: Must be either `true` or `false`. If an option is a boolean,
105 then it does not need a value, and its presence will imply `true` as
106 the value. To negate boolean flags, do `--no-whatever` or `--whatever
108 * NaN: Means that the option is strictly not allowed. Any value will
110 * Stream: An object matching the "Stream" class in node. Valuable
111 for use when validating programmatically. (npm uses this to let you
112 supply any WriteStream on the `outfd` and `logfd` config options.)
113 * Array: If `Array` is specified as one of the types, then the value
114 will be parsed as a list of options. This means that multiple values
115 can be specified, and that the value will always be an array.
117 If a type is an array of values not on this list, then those are
118 considered valid values. For instance, in the example above, the
119 `--bloo` option can only be one of `"big"`, `"medium"`, or `"small"`,
120 and any other value will be rejected.
122 When parsing unknown fields, `"true"`, `"false"`, and `"null"` will be
123 interpreted as their JavaScript equivalents.
125 You can also mix types and values, or multiple types, in a list. For
126 instance `{ blah: [Number, null] }` would allow a value to be set to
127 either a Number or null. When types are ordered, this implies a
128 preference, and the first type that can be used to properly interpret
129 the value will be used.
131 To define a new type, add it to `nopt.typeDefs`. Each item in that
132 hash is an object with a `type` member and a `validate` method. The
133 `type` member is an object that matches what goes in the type list. The
134 `validate` method is a function that gets called with `validate(data,
135 key, val)`. Validate methods should assign `data[key]` to the valid
136 value of `val` if it can be handled properly, or return boolean
137 `false` if it cannot.
139 You can also call `nopt.clean(data, types, typeDefs)` to clean up a
140 config object and remove its invalid properties.
144 By default, nopt outputs a warning to standard error when invalid values for
145 known options are found. You can change this behavior by assigning a method
146 to `nopt.invalidHandler`. This method will be called with
147 the offending `nopt.invalidHandler(key, val, types)`.
149 If no `nopt.invalidHandler` is assigned, then it will console.error
150 its whining. If it is assigned to boolean `false` then the warning is
155 Yes, they are supported. If you define options like this:
158 { "foolhardyelephants" : Boolean
159 , "pileofmonkeys" : Boolean }
165 node program.js --foolhar --pil
166 node program.js --no-f --pileofmon
172 Shorthands are a hash of shorter option names to a snippet of args that
175 If multiple one-character shorthands are all combined, and the
176 combination does not unambiguously match any other option or shorthand,
177 then they will be broken up into their constituent parts. For example:
180 { "s" : ["--loglevel", "silent"]
183 , "p" : "--parseable"
190 # just like doing this:
191 npm ls --loglevel silent --global --force --long --parseable
194 ## The Rest of the args
196 The config object returned by nopt is given a special member called
197 `argv`, which is an object with the following fields:
199 * `remain`: The remaining args after all the parsing has occurred.
200 * `original`: The args as they originally appeared.
201 * `cooked`: The args after flags and shorthands are expanded.
205 Node programs are called with more or less the exact argv as it appears
206 in C land, after the v8 and node-specific options have been plucked off.
207 As such, `argv[0]` is always `node` and `argv[1]` is always the
208 JavaScript program being run.
210 That's usually not very useful to you. So they're sliced off by
211 default. If you want them, then you can pass in `0` as the last
212 argument, or any other number that you'd like to slice off the start of