PACKAGE.JSON(5) PACKAGE.JSON(5)
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.
A lot of the behavior described in this document is affected by the
config settings described in npm help config.
name
If you plan to publish your package, the most important things in your
package.json are the name and version fields as they will be required.
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. If you don't plan to publish your package, the
name and version fields are optional.
The name is what your thing is called.
Some rules:
o The name must be less than or equal to 214 characters. This
includes the scope for scoped packages.
o The names of scoped packages can begin with a dot or an underscore.
This is not permitted without a scope.
o New packages must not have uppercase letters in the name.
o The name ends up being part of a URL, an argument on the command
line, and a folder name. Therefore, the name can't contain any non-
URL-safe characters.
Some tips:
o Don't use the same name as a core Node module.
o 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 (engines)" field. (See below.)
o The name will probably be passed as an argument to require(), so it
should be something short, but also reasonably descriptive.
o 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.
<https://www.npmjs.com/>
A name can be optionally prefixed by a scope, e.g. @myorg/mypackage.
See npm help scope for more detail.
version
If you plan to publish your package, the most important things in your
package.json are the name and version fields as they will be required.
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. If you don't plan to publish your package, the
name and version fields are optional.
Version must be parseable by node-semver <https://github.com/npm/node-
semver>, which is bundled with npm as a dependency. (npm install semver
to use it yourself.)
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.
Example:
"homepage": "https://github.com/owner/project#readme"
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:
{
"bugs": {
"url": "https://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.
If you're using a common license such as BSD-2-Clause or MIT, add a
current SPDX license identifier for 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
<https://opensource.org/licenses/> approved.
If your package is licensed under multiple common licenses, use an SPDX
license expression syntax version 2.0 string
<https://spdx.dev/specifications/>, like this:
{
"license" : "(ISC OR GPL-3.0)"
}
If you are using a license that hasn't been assigned an SPDX
identifier, or if you are using a custom license, use a string value
like this one:
{
"license" : "SEE LICENSE IN <filename>"
}
Then include a file named <filename> at the top level of the package.
Some old packages used license objects or a "licenses" property
containing an array of license objects:
// Not valid metadata
{
"license" : {
"type" : "ISC",
"url" : "https://opensource.org/licenses/ISC"
}
}
// Not valid metadata
{
"licenses" : [
{
"type": "MIT",
"url": "https://www.opensource.org/licenses/mit-license.php"
},
{
"type": "Apache-2.0",
"url": "https://opensource.org/licenses/apache2.0.php"
}
]
}
Those styles are now deprecated. Instead, use SPDX expressions, like
this:
{
"license": "ISC"
}
{
"license": "(MIT OR Apache-2.0)"
}
Finally, if you do not wish to grant others the right to use a private
or unpublished package under any terms:
{
"license": "UNLICENSED"
}
Consider also setting "private": true to prevent accidental
publication.
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:
{
"author": "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.
funding
You can specify an object containing a URL that provides up-to-date
information about ways to help fund development of your package, a
string URL, or an array of objects and string URLs:
{
"funding": {
"type" : "individual",
"url" : "http://example.com/donate"
}
}
{
"funding": {
"type" : "patreon",
"url" : "https://www.patreon.com/my-account"
}
}
{
"funding": "http://example.com/donate"
}
{
"funding": [
{
"type" : "individual",
"url" : "http://example.com/donate"
},
"http://example.com/donateAlso",
{
"type" : "patreon",
"url" : "https://www.patreon.com/my-account"
}
]
}
Users can use the npm fund subcommand to list the funding URLs of all
dependencies of their project, direct and indirect. A shortcut to visit
each funding URL is also available when providing the project name such
as: npm fund <projectname> (when there are multiple URLs, the first one
will be visited)
files
The optional files field is an array of file patterns that describes
the entries to be included when your package is installed as a
dependency. File patterns follow a similar syntax to .gitignore, but
reversed: including a file, directory, or glob pattern (*, **/*, and
such) will make it so that file is included in the tarball when it's
packed. Omitting the field will make it default to ["*"], which means
it will include all files.
Some special files and directories are also included or excluded
regardless of whether they exist in the files array (see below).
You can also provide a .npmignore file in the root of your package or
in subdirectories, which will keep files from being included. At the
root of your package it will not override the "files" field, but in
subdirectories it will. The .npmignore file works just like a
.gitignore. If there is a .gitignore file, and .npmignore is missing,
.gitignore's contents will be used instead.
Certain files are always included, regardless of settings:
o package.json
o README
o LICENSE / LICENCE
o The file in the "main" field
o The file(s) in the "bin" field
README & LICENSE can have any case and extension.
Some files are always ignored by default:
o *.orig
o .*.swp
o .DS_Store
o ._*
o .git
o .hg
o .lock-wscript
o .npmrc
o .svn
o .wafpickle-N
o CVS
o config.gypi
o node_modules
o npm-debug.log
o package-lock.json (use npm-shrinkwrap.json </configuring-npm/npm-
shrinkwrap-json> if you wish it to be published)
o pnpm-lock.yaml
o yarn.lock
Most of these ignored files can be included specifically if included in
the files globs. Exceptions to this are:
o .git
o .npmrc
o node_modules
o package-lock.json
o pnpm-lock.yaml
o yarn.lock
These can not be included.
exports
The "exports" provides a modern alternative to "main" allowing multiple
entry points to be defined, conditional entry resolution support
between environments, and preventing any other entry points besides
those defined in "exports". This encapsulation allows module authors to
clearly define the public interface for their package. For more details
see the node.js documentation on package entry points
<https://nodejs.org/api/packages.html#package-entry-points>
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 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.
If main is not set, it defaults to index.js in the package's root
folder.
browser
If your module is meant to be used client-side the browser field should
be used instead of the main field. This is helpful to hint users that
it might rely on primitives that aren't available in Node.js modules.
(e.g. window)
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. When this package is installed
globally, that file will be either linked inside the global bins
directory or a cmd (Windows Command File) will be created which
executes the specified file in the bin field, so it is available to run
by name or name.cmd (on Windows PowerShell). When this package is
installed as a dependency in another package, the file will be linked
where it will be available to that package either directly by npm exec
or by name in other scripts when invoking them via npm run-script.
For example, myapp could have this:
{
"bin": {
"myapp": "bin/cli.js"
}
}
So, when you install myapp, in case of unix-like OS it'll create a
symlink from the cli.js script to /usr/local/bin/myapp and in case of
windows it will create a cmd file usually at
C:\Users\{Username}\AppData\Roaming\npm\myapp.cmd which runs the cli.js
script.
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"
}
}
Please make sure that your file(s) referenced in bin starts with
#!/usr/bin/env node, otherwise the scripts are started without the node
executable!
Note that you can also set the executable files using directories.bin
(directories.bin).
See folders </configuring-npm/folders#executables> for more info on
executables.
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 object. If you look at npm's package.json
<https://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.bin
If you specify a bin directory in directories.bin, all the files in
that folder will be added.
Because of the way the bin directive works, specifying both a bin path
and setting directories.bin is an error. If you want to specify
individual files, use bin, and for all the files in an existing bin
directory, use directories.bin.
directories.man
A folder that is full of man pages. Sugar to generate a "man" array by
walking the folder.
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 repo
command will be able to find you.
Do it like this:
{
"repository": {
"type": "git",
"url": "git+https://github.com/npm/cli.git"
}
}
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.
For GitHub, GitHub gist, Bitbucket, or GitLab repositories you can use
the same shortcut syntax you use for npm install:
{
"repository": "npm/npm",
"repository": "github:user/repo",
"repository": "gist:11081aaa281",
"repository": "bitbucket:user/repo",
"repository": "gitlab:user/repo"
}
If the package.json for your package is not in the root directory (for
example if it is part of a monorepo), you can specify the directory in
which it lives:
{
"repository": {
"type": "git",
"url": "git+https://github.com/npm/cli.git",
"directory": "workspaces/libnpmpublish"
}
}
scripts
The "scripts" property is a dictionary containing 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.
See npm help scripts to find out more about writing package scripts.
config
A "config" object 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"
}
}
It could also have a "start" command that referenced the
npm_package_config_port environment variable.
dependencies
Dependencies are specified in a simple object that maps a package name
to a 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 or other "development"
time tools in your dependencies object. See devDependencies, below.
See semver <https://github.com/npm/node-semver#versions> for more
details about specifying version ranges.
o version Must match version exactly
o >version Must be greater than version
o >=version etc
o <version
o <=version
o ~version "Approximately equivalent to version" See semver
<https://github.com/npm/node-semver#versions>
o ^version "Compatible with version" See semver
<https://github.com/npm/node-semver#versions>
o 1.2.x 1.2.0, 1.2.1, etc., but not 1.3.0
o http://... See 'URLs as Dependencies' below
o * Matches any version
o "" (just an empty string) Same as *
o version1 - version2 Same as >=version1 <=version2.
o range1 || range2 Passes if either range1 or range2 are satisfied.
o git... See 'Git URLs as Dependencies' below
o user/repo See 'GitHub URLs' below
o tag A specific version tagged and published as tag See npm help
dist-tag
o path/path/path See Local Paths (Local Paths) below
o npm:@scope/pkg@version Custom alias for a pacakge See package-spec
</using-npm/package-spec#aliases>
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",
"lat": "latest",
"dyl": "file:../dyl",
"kpg": "npm:pkg@1.0.0"
}
}
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 are of the form:
<protocol>://[<user>[:<password>]@]<hostname>[:<port>][:][/]<path>[#<commit-ish> | #semver:<semver>]
<protocol> is one of git, git+ssh, git+http, git+https, or git+file.
If #<commit-ish> is provided, it will be used to clone exactly that
commit. If the commit-ish has the format #semver:<semver>, <semver> can
be any valid semver range or exact version, and npm will look for any
tags or refs matching that range in the remote repository, much as it
would for a registry dependency. If neither #<commit-ish> or
#semver:<semver> is specified, then the default branch is used.
Examples:
git+ssh://git@github.com:npm/cli.git#v1.0.27
git+ssh://git@github.com:npm/cli#semver:^5.0
git+https://isaacs@github.com/npm/cli.git
git://github.com/npm/cli.git#v1.0.27
When installing from a git repository, the presence of certain fields
in the package.json will cause npm to believe it needs to perform a
build. To do so your repository will be cloned into a temporary
directory, all of its deps installed, relevant scripts run, and the
resulting directory packed and installed.
This flow will occur if your git dependency uses workspaces, or if any
of the following scripts are present:
o build
o prepare
o prepack
o preinstall
o install
o postinstall
If your git repository includes pre-built artifacts, you will likely
want to make sure that none of the above scripts are defined, or your
dependency will be rebuilt for every installation.
GitHub URLs
As of version 1.1.65, you can refer to GitHub URLs as just "foo":
"user/foo-project". Just as with git URLs, a commit-ish suffix can be
included. For example:
{
"name": "foo",
"version": "0.0.0",
"dependencies": {
"express": "expressjs/express",
"mocha": "mochajs/mocha#4727d357ea",
"module": "user/repo#feature\/branch"
}
}
Local Paths
As of version 2.0.0 you can provide a path to a local directory that
contains a package. Local paths can be saved using npm install -S or
npm install --save, using any of these forms:
~/foo/bar
/foo/bar
in which case they will be normalized to a relative path and added to
your package.json. For example:
{
"name": "baz",
"dependencies": {
"bar": "file:../foo/bar"
}
}
This feature is helpful for local offline development and creating
tests that require npm installing where you don't want to hit an
external server, but should not be used when publishing your package to
the public registry.
note: Packages linked by local path will not have their own
dependencies installed when npm install is ran in this case. You must
run npm install from inside the local path itself.
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 map these additional items in a
devDependencies object.
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 help 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 prepare 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": {
"prepare": "coffee -o lib/ -c src/waza.coffee"
},
"main": "lib/waza.js"
}
The prepare 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 a host tool or library, while not necessarily doing a require of
this host. This is usually referred 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. npm install tea-
latte could possibly yield the following dependency graph:
<?><?><?> tea-latte@1.3.5
<?><?><?> tea@2.2.0
In npm versions 3 through 6, peerDependencies were not automatically
installed, and would raise a warning if an invalid version of the peer
dependency was found in the tree. As of npm v7, peerDependencies are
installed by default.
Trying to install another plugin with a conflicting requirement may
cause an error if the tree cannot be resolved correctly. 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 <https://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".
peerDependenciesMeta
The peerDependenciesMeta field serves to provide npm more information
on how your peer dependencies are to be used. Specifically, it allows
peer dependencies to be marked as optional. Npm will not automatically
install optional peer dependencies. This allows you to integrate and
interact with a variety of host packages without requiring all of them
to be installed.
For example:
{
"name": "tea-latte",
"version": "1.3.5",
"peerDependencies": {
"tea": "2.x",
"soy-milk": "1.2"
},
"peerDependenciesMeta": {
"soy-milk": {
"optional": true
}
}
}
bundleDependencies
This defines an array of package names that will be bundled when
publishing the package.
In cases where you need to preserve npm packages locally or have them
available through a single file download, you can bundle the packages
in a tarball file by specifying the package names in the
bundleDependencies array and executing npm pack.
For example:
If we define a package.json like this:
{
"name": "awesome-web-framework",
"version": "1.0.0",
"bundleDependencies": [
"renderized",
"super-streams"
]
}
we can obtain awesome-web-framework-1.0.0.tgz file by running npm pack.
This file contains the dependencies renderized and super-streams which
can be installed in a new project by executing npm install awesome-web-
framework-1.0.0.tgz. Note that the package names do not include any
versions, as that information is specified in dependencies.
If this is spelled "bundledDependencies", then that is also honored.
Alternatively, "bundleDependencies" can be defined as a boolean value.
A value of true will bundle all dependencies, a value of false will
bundle none.
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 object. This is a map of package name to version
or URL, just like the dependencies object. The difference is that build
failures do not cause installation to fail. Running npm install
--omit=optional will prevent these dependencies from being installed.
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.
overrides
If you need to make specific changes to dependencies of your
dependencies, for example replacing the version of a dependency with a
known security issue, replacing an existing dependency with a fork, or
making sure that the same version of a package is used everywhere, then
you may add an override.
Overrides provide a way to replace a package in your dependency tree
with another version, or another package entirely. These changes can be
scoped as specific or as vague as desired.
Overrides are only considered in the root package.json file for a
project. Overrides in installed dependencies (including npm help
workspaces) are not considered in dependency tree resolution. Published
packages may dictate their resolutions by pinning dependencies or using
an npm-shrinkwrap.json </configuring-npm/npm-shrinkwrap-json> file.
To make sure the package foo is always installed as version 1.0.0 no
matter what version your dependencies rely on:
{
"overrides": {
"foo": "1.0.0"
}
}
The above is a short hand notation, the full object form can be used to
allow overriding a package itself as well as a child of the package.
This will cause foo to always be 1.0.0 while also making bar at any
depth beyond foo also 1.0.0:
{
"overrides": {
"foo": {
".": "1.0.0",
"bar": "1.0.0"
}
}
}
To only override foo to be 1.0.0 when it's a child (or grandchild, or
great grandchild, etc) of the package bar:
{
"overrides": {
"bar": {
"foo": "1.0.0"
}
}
}
Keys can be nested to any arbitrary length. To override foo only when
it's a child of bar and only when bar is a child of baz:
{
"overrides": {
"baz": {
"bar": {
"foo": "1.0.0"
}
}
}
}
The key of an override can also include a version, or range of
versions. To override foo to 1.0.0, but only when it's a child of
bar@2.0.0:
{
"overrides": {
"bar@2.0.0": {
"foo": "1.0.0"
}
}
}
You may not set an override for a package that you directly depend on
unless both the dependency and the override itself share the exact same
spec. To make this limitation easier to deal with, overrides may also
be defined as a reference to a spec for a direct dependency by
prefixing the name of the package you wish the version to match with a
$.
{
"dependencies": {
"foo": "^1.0.0"
},
"overrides": {
// BAD, will throw an EOVERRIDE error
// "foo": "^2.0.0"
// GOOD, specs match so override is allowed
// "foo": "^1.0.0"
// BEST, the override is defined as a reference to the dependency
"foo": "$foo",
// the referenced package does not need to match the overridden one
"bar": "$foo"
}
}
engines
You can specify the version of node that your stuff works on:
{
"engines": {
"node": ">=0.10.3 <15"
}
}
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.
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"
}
}
Unless the user has set the engine-strict config </using-
npm/config#engine-strict> flag, this field is advisory only and will
only produce warnings when your package is installed as a dependency.
os
You can specify which operating systems your module will run on:
{
"os": [
"darwin",
"linux"
]
}
You can also block instead of allowing operating systems, just prepend
the blocked os with a '!':
{
"os": [
"!win32"
]
}
The host operating system is determined by process.platform
It is allowed to both block and allow an item, 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 block architectures:
{
"cpu": [
"!arm",
"!mips"
]
}
The host architecture is determined by process.arch
devEngines
The devEngines field aids engineers working on a codebase to all be
using the same tooling.
You can specify a devEngines property in your package.json which will
run before install, ci, and run commands.
Note: engines and devEngines differ in object shape. They also function
very differently. engines is designed to alert the user when a
dependency uses a differening npm or node version that the project it's
being used in, whereas devEngines is used to alert people interacting
with the source code of a project.
The supported keys under the devEngines property are cpu, os, libc,
runtime, and packageManager. Each property can be an object or an array
of objects. Objects must contain name, and optionally can specify
version, and onFail. onFail can be warn, error, or ignore, and if left
undefined is of the same value as error. npm will assume that you're
running with node. Here's an example of a project that will fail if the
environment is not node and npm. If you set runtime.name or
packageManager.name to any other string, it will fail within the npm
CLI.
{
"devEngines": {
"runtime": {
"name": "node",
"onFail": "error"
},
"packageManager": {
"name": "npm",
"onFail": "error"
}
}
}
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 dictionary 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, registry or access, so
that you can ensure that a given package is not tagged with "latest",
published to the global public registry or that a scoped module is
private by default.
See npm help config to see the list of config options that can be
overridden.
workspaces
The optional workspaces field is an array of file patterns that
describes locations within the local file system that the install
client should look up to find each npm help workspace that needs to be
symlinked to the top level node_modules folder.
It can describe either the direct paths of the folders to be used as
workspaces or it can define globs that will resolve to these same
folders.
In the following example, all folders located inside the folder
./packages will be treated as workspaces as long as they have valid
package.json files inside them:
{
"name": "workspace-example",
"workspaces": [
"./packages/*"
]
}
See npm help workspaces for more examples.
DEFAULT VALUES
npm will default some values based on package contents.
o "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.
o "scripts":{"install": "node-gyp rebuild"}
If there is a binding.gyp file in the root of your package and you have
not defined an install or preinstall script, npm will default the
install command to compile using node-gyp.
o "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
o semver <https://github.com/npm/node-semver#versions>
o npm help workspaces
o npm help init
o npm help version
o npm help config
o npm help help
o npm help install
o npm help publish
o npm help uninstall
NPM@10.9.0 October 2024 PACKAGE.JSON(5)
npm 10.9.0 - Generated Wed Nov 27 15:54:09 CST 2024