NAME¶
package.json - Specifics of npm´s package.json handling
DESCRIPTION¶
This document is all you need to know about what´s required in your
package.json file. It must be actual JSON, not just a JavaScript object
literal.
npm help A lot of the behavior described in this document is affected by the
config settings described in
npm-config.
name¶
The
most important things in your package.json are the name and version
fields. Those are actually required, and your package won´t install
without them. The name and version together form an identifier that is assumed
to be completely unique. Changes to the package should come along with changes
to the version.
The name is what your thing is called. Some tips:
- •
- Don´t put "js" or "node" in the name.
It´s assumed that it´s js, since you´re writing a
package.json file, and you can specify the engine using the
"engines" field. (See below.)
- •
- The name ends up being part of a URL, an argument on the command line, and
a folder name. Any name with non-url-safe characters will be rejected.
Also, it can´t start with a dot or an underscore.
- •
- The name will probably be passed as an argument to require(), so it should
be something short, but also reasonably descriptive.
- •
- You may want to check the npm registry to see if there´s something
by that name already, before you get too attached to it.
http://registry.npmjs.org/
-
version¶
The
most important things in your package.json are the name and version
fields. Those are actually required, and your package won´t install
without them. The name and version together form an identifier that is assumed
to be completely unique. Changes to the package should come along with changes
to the version.
Version must be parseable by node-semver
https://github.com/isaacs/node-semver, which is bundled with npm as a
dependency. (
npm install semver to use it yourself.)
npm help More on version numbers and ranges at semver.
description¶
Put a description in it. It´s a string. This helps people discover your
package, as it´s listed in
npm search.
keywords¶
Put keywords in it. It´s an array of strings. This helps people discover
your package as it´s listed in
npm search.
homepage¶
The url to the project homepage.
NOTE: This is
not the same as "url". If you put a
"url" field, then the registry will think it´s a redirection
to your package that has been published somewhere else, and spit at you.
Literally. Spit. I´m so not kidding.
bugs¶
The url to your project´s issue tracker and / or the email address to
which issues should be reported. These are helpful for people who encounter
issues with your package.
It should look like this:
-
-
{ "url" : "http://github.com/owner/project/issues"
, "email" : "project@hostname.com"
}
-
You can specify either one or both values. If you want to provide only a url,
you can specify the value for "bugs" as a simple string instead of
an object.
If a url is provided, it will be used by the
npm bugs command.
license¶
You should specify a license for your package so that people know how they are
permitted to use it, and any restrictions you´re placing on it.
The simplest way, assuming you´re using a common license such as
BSD-3-Clause or MIT, is to just specify the standard SPDX ID of the license
you´re using, like this:
-
-
{ "license" : "BSD-3-Clause" }
-
You can check the full list of SPDX license IDs
https://spdx.org/licenses/. Ideally you should pick one that is OSI
http://opensource.org/licenses/alphabetical approved.
It´s also a good idea to include a LICENSE file at the top level in your
package.
people fields: author, contributors¶
The "author" is one person. "contributors" is an array of
people. A "person" is an object with a "name" field and
optionally "url" and "email", like this:
-
-
{ "name" : "Barney Rubble"
, "email" : "b@rubble.com"
, "url" : "http://barnyrubble.tumblr.com/"
}
-
Or you can shorten that all into a single string, and npm will parse it for you:
-
-
"Barney Rubble <b@rubble.com> (http://barnyrubble.tumblr.com/)
-
Both email and url are optional either way.
npm also sets a top-level "maintainers" field with your npm user info.
files¶
The "files" field is an array of files to include in your project. If
you name a folder in the array, then it will also include the files inside
that folder. (Unless they would be ignored by another rule.)
You can also provide a ".npmignore" file in the root of your package,
which will keep files from being included, even if they would be picked up by
the files array. The ".npmignore" file works just like a
".gitignore".
main¶
The main field is a module ID that is the primary entry point to your program.
That is, if your package is named
foo, and a user installs it, and then
does
require("foo"), then your main module´s exports
object will be returned.
This should be a module ID relative to the root of your package folder.
For most modules, it makes the most sense to have a main script and often not
much else.
bin¶
A lot of packages have one or more executable files that they´d like to
install into the PATH. npm makes this pretty easy (in fact, it uses this
feature to install the "npm" executable.)
To use this, supply a
bin field in your package.json which is a map of
command name to local file name. On install, npm will symlink that file into
prefix/bin for global installs, or
./node_modules/.bin/ for
local installs.
For example, npm has this:
-
-
{ "bin" : { "npm" : "./cli.js" } }
-
So, when you install npm, it´ll create a symlink from the
cli.js
script to
/usr/local/bin/npm.
If you have a single executable, and its name should be the name of the package,
then you can just supply it as a string. For example:
-
-
{ "name": "my-program"
, "version": "1.2.5"
, "bin": "./path/to/program" }
-
would be the same as this:
-
-
{ "name": "my-program"
, "version": "1.2.5"
, "bin" : { "my-program" : "./path/to/program" } }
-
man¶
Specify either a single file or an array of filenames to put in place for the
man program to find.
If only a single file is provided, then it´s installed such that it is
the result from
man <pkgname>, regardless of its actual filename.
For example:
-
-
{ "name" : "foo"
, "version" : "1.2.3"
, "description" : "A packaged foo fooer for fooing foos"
, "main" : "foo.js"
, "man" : "./man/doc.1"
}
-
would link the
./man/doc.1 file in such that it is the target for
man
foo
If the filename doesn´t start with the package name, then it´s
prefixed. So, this:
-
-
{ "name" : "foo"
, "version" : "1.2.3"
, "description" : "A packaged foo fooer for fooing foos"
, "main" : "foo.js"
, "man" : [ "./man/foo.1", "./man/bar.1" ]
}
-
will create files to do
man foo and
man foo-bar.
Man files must end with a number, and optionally a
.gz suffix if they are
compressed. The number dictates which man section the file is installed into.
-
-
{ "name" : "foo"
, "version" : "1.2.3"
, "description" : "A packaged foo fooer for fooing foos"
, "main" : "foo.js"
, "man" : [ "./man/foo.1", "./man/foo.2" ]
}
-
will create entries for
man foo and
man 2 foo
directories¶
The CommonJS Packages
http://wiki.commonjs.org/wiki/Packages/1.0 spec
details a few ways that you can indicate the structure of your package using a
directories hash. If you look at npm´s package.json
http://registry.npmjs.org/npm/latest, you´ll see that it has
directories for doc, lib, and man.
In the future, this information may be used in other creative ways.
directories.lib¶
Tell people where the bulk of your library is. Nothing special is done with the
lib folder in any way, but it´s useful meta info.
directories.bin¶
If you specify a "bin" directory, then all the files in that folder
will be used as the "bin" hash.
If you have a "bin" hash already, then this has no effect.
directories.man¶
A folder that is full of man pages. Sugar to generate a "man" array by
walking the folder.
directories.doc¶
Put markdown files in here. Eventually, these will be displayed nicely, maybe,
someday.
directories.example¶
Put example scripts in here. Someday, it might be exposed in some clever way.
repository¶
Specify the place where your code lives. This is helpful for people who want to
contribute. If the git repo is on github, then the
npm docs command
will be able to find you.
Do it like this:
-
-
"repository" :
{ "type" : "git"
, "url" : "http://github.com/npm/npm.git"
}
"repository" :
{ "type" : "svn"
, "url" : "http://v8.googlecode.com/svn/trunk/"
}
-
The URL should be a publicly available (perhaps read-only) url that can be
handed directly to a VCS program without any modification. It should not be a
url to an html project page that you put in your browser. It´s for
computers.
scripts¶
The "scripts" member is an object hash of script commands that are run
at various times in the lifecycle of your package. The key is the lifecycle
event, and the value is the command to run at that point.
npm help See
npm-scripts to find out more about writing package scripts.
config¶
A "config" hash can be used to set configuration parameters used in
package scripts that persist across upgrades. For instance, if a package had
the following:
-
-
{ "name" : "foo"
, "config" : { "port" : "8080" } }
-
and then had a "start" command that then referenced the
npm_package_config_port environment variable, then the user could
override that by doing
npm config set foo:port 8001.
npm help See
npm-confignpm help and
npm-scripts for more on
package configs.
dependencies¶
Dependencies are specified with a simple hash of package name to version range.
The version range is a string which has one or more space-separated
descriptors. Dependencies can also be identified with a tarball or git URL.
Please do not put test harnesses or transpilers in your
dependencies hash. See
devDependencies, below.
npm help See semver for more details about specifying version ranges.
- •
- version Must match version exactly
- •
- >version Must be greater than version
- •
- >=version etc
- •
- <version
- •
- <=version
- •
- npm help ~version "Approximately equivalent to version"
See semver
- •
- npm help ^version "Compatible with version" See
semver
- •
- 1.2.x 1.2.0, 1.2.1, etc., but not 1.3.0
- •
- http://... See ´URLs as Dependencies´ below
- •
- * Matches any version
- •
- "" (just an empty string) Same as *
- •
- version1 - version2 Same as >=version1
<=version2.
- •
- range1 || range2 Passes if either range1 or range2 are
satisfied.
- •
- git... See ´Git URLs as Dependencies´ below
- •
- user/repo See ´GitHub URLs´ below
-
For example, these are all valid:
-
-
{ "dependencies" :
{ "foo" : "1.0.0 - 2.9999.9999"
, "bar" : ">=1.0.2 <2.1.2"
, "baz" : ">1.0.2 <=2.3.4"
, "boo" : "2.0.1"
, "qux" : "<1.0.0 || >=2.3.1 <2.4.5 || >=2.5.2 <3.0.0"
, "asd" : "http://asdf.com/asdf.tar.gz"
, "til" : "~1.2"
, "elf" : "~1.2.3"
, "two" : "2.x"
, "thr" : "3.3.x"
}
}
-
URLs as Dependencies¶
You may specify a tarball URL in place of a version range.
This tarball will be downloaded and installed locally to your package at install
time.
Git URLs as Dependencies¶
Git urls can be of the form:
-
-
git://github.com/user/project.git#commit-ish
git+ssh://user@hostname:project.git#commit-ish
git+ssh://user@hostname/project.git#commit-ish
git+http://user@hostname/project/blah.git#commit-ish
git+https://user@hostname/project/blah.git#commit-ish
-
The
commit-ish can be any tag, sha, or branch which can be supplied as an
argument to
git checkout. The default is
master.
GitHub URLs¶
As of version 1.1.65, you can refer to GitHub urls as just "foo":
"user/foo-project". For example:
-
-
{
"name": "foo",
"version": "0.0.0",
"dependencies": {
"express": "visionmedia/express"
}
}
-
devDependencies¶
If someone is planning on downloading and using your module in their program,
then they probably don´t want or need to download and build the
external test or documentation framework that you use.
In this case, it´s best to list these additional items in a
devDependencies hash.
npm help These things will be installed when doing
npm link or
npm
install from the root of a package, and can be managed like any other npm
configuration param. See
npm-config for more on the topic.
For build steps that are not platform-specific, such as compiling CoffeeScript
or other languages to JavaScript, use the
prepublish script to do this,
and make the required package a devDependency.
For example:
-
-
{ "name": "ethopia-waza",
"description": "a delightfully fruity coffee varietal",
"version": "1.2.3",
"devDependencies": {
"coffee-script": "~1.6.3"
},
"scripts": {
"prepublish": "coffee -o lib/ -c src/waza.coffee"
},
"main": "lib/waza.js"
}
-
The
prepublish script will be run before publishing, so that users can
consume the functionality without requiring them to compile it themselves. In
dev mode (ie, locally running
npm install), it´ll run this
script as well, so that you can test it easily.
peerDependencies¶
In some cases, you want to express the compatibility of your package with an
host tool or library, while not necessarily doing a
require of this
host. This is usually refered to as a
plugin. Notably, your module may
be exposing a specific interface, expected and specified by the host
documentation.
For example:
-
-
{
"name": "tea-latte",
"version": "1.3.5"
"peerDependencies": {
"tea": "2.x"
}
}
-
This ensures your package
tea-latte can be installed
along with
the second major version of the host package
tea only. The host package
is automatically installed if needed.
npm install tea-latte could
possibly yield the following dependency graph:
-
-
|-- tea-latte@1.3.5
|-- tea@2.2.0
-
Trying to install another plugin with a conflicting requirement will cause an
error. For this reason, make sure your plugin requirement is as broad as
possible, and not to lock it down to specific patch versions.
Assuming the host complies with semver
http://semver.org/, only changes
in the host package´s major version will break your plugin. Thus, if
you´ve worked with every 1.x version of the host package, use
"^1.0" or
"1.x" to express this. If you
depend on features introduced in 1.5.2, use
">= 1.5.2 <
2".
bundledDependencies¶
Array of package names that will be bundled when publishing the package.
If this is spelled
"bundleDependencies", then that is also
honorable.
optionalDependencies¶
If a dependency can be used, but you would like npm to proceed if it cannot be
found or fails to install, then you may put it in the
optionalDependencies hash. This is a map of package name to version or
url, just like the
dependencies hash. The difference is that failure is
tolerated.
It is still your program´s responsibility to handle the lack of the
dependency. For example, something like this:
-
-
try {
var foo = require(´foo´)
var fooVersion = require(´foo/package.json´).version
} catch (er) {
foo = null
}
if ( notGoodFooVersion(fooVersion) ) {
foo = null
}
// .. then later in your program ..
if (foo) {
foo.doFooThings()
}
-
Entries in
optionalDependencies will override entries of the same name in
dependencies, so it´s usually best to only put in one place.
engines¶
You can specify the version of node that your stuff works on:
-
-
{ "engines" : { "node" : ">=0.10.3 <0.12" } }
-
And, like with dependencies, if you don´t specify the version (or if you
specify "*" as the version), then any version of node will do.
If you specify an "engines" field, then npm will require that
"node" be somewhere on that list. If "engines" is omitted,
then npm will just assume that it works on node.
You can also use the "engines" field to specify which versions of npm
are capable of properly installing your program. For example:
-
-
{ "engines" : { "npm" : "~1.0.20" } }
-
Note that, unless the user has set the
engine-strict config flag, this
field is advisory only.
engineStrict¶
If you are sure that your module will
definitely not run properly on
versions of Node/npm other than those specified in the
engines hash,
then you can set
"engineStrict": true in your package.json
file. This will override the user´s
engine-strict config
setting.
Please do not do this unless you are really very very sure. If your engines hash
is something overly restrictive, you can quite easily and inadvertently lock
yourself into obscurity and prevent your users from updating to new versions
of Node. Consider this choice carefully. If people abuse it, it will be
removed in a future version of npm.
You can specify which operating systems your module will run on:
-
-
"os" : [ "darwin", "linux" ]
-
You can also blacklist instead of whitelist operating systems, just prepend the
blacklisted os with a ´!´:
-
-
"os" : [ "!win32" ]
-
The host operating system is determined by
process.platform
It is allowed to both blacklist, and whitelist, although there isn´t any
good reason to do this.
cpu¶
If your code only runs on certain cpu architectures, you can specify which ones.
-
-
"cpu" : [ "x64", "ia32" ]
-
Like the
os option, you can also blacklist architectures:
-
-
"cpu" : [ "!arm", "!mips" ]
-
The host architecture is determined by
process.arch
preferGlobal¶
If your package is primarily a command-line application that should be installed
globally, then set this value to
true to provide a warning if it is
installed locally.
It doesn´t actually prevent users from installing it locally, but it does
help prevent some confusion if it doesn´t work as expected.
private¶
If you set
"private": true in your package.json, then npm will
refuse to publish it.
This is a way to prevent accidental publication of private repositories. If you
would like to ensure that a given package is only ever published to a specific
registry (for example, an internal registry), then use the
publishConfig hash described below to override the
registry
config param at publish-time.
publishConfig¶
This is a set of config values that will be used at publish-time. It´s
especially handy if you want to set the tag or registry, so that you can
ensure that a given package is not tagged with "latest" or published
to the global public registry by default.
Any config values can be overridden, but of course only "tag" and
"registry" probably matter for the purposes of publishing.
npm help See
npm-config to see the list of config options that can be
overridden.
DEFAULT VALUES¶
npm will default some values based on package contents.
- •
- "scripts": {"start": "node
server.js"}
- If there is a server.js file in the root of your package, then npm
will default the start command to node server.js.
- •
- "scripts":{"preinstall": "node-gyp
rebuild"}
- If there is a binding.gyp file in the root of your package, npm
will default the preinstall command to compile using node-gyp.
- •
- "contributors": [...]
- If there is an AUTHORS file in the root of your package, npm will
treat each line as a Name <email> (url) format, where email
and url are optional. Lines which start with a # or are blank, will
be ignored.
-
SEE ALSO¶
- •
- npm help semver
- •
- npm help init
- •
- npm help version
- •
- npm help config
- •
- npm help config
- •
- npm help help
- •
- npm help faq
- •
- npm help install
- •
- npm help publish
- •
- npm help rm
-
-