1 ---
2 title: package.json
3 section: 5
4 description: Specifics of npm's package.json handling
5 github_repo: npm/cli
6 github_branch: latest
7 github_path: docs/lib/content/configuring-npm/package-json.md
8 redirect_from:
9 - /cli-documentation/configuring-npm/package-json
10 - /cli-documentation/configuring-npm/package.json
11 - /cli-documentation/files/package-json
12 - /cli-documentation/files/package.json
13 - /cli-documentation/v10/configuring-npm/package-json
14 - /cli-documentation/v10/configuring-npm/package.json
15 - /cli-documentation/v10/files/package-json
16 - /cli-documentation/v10/files/package.json
17 - /cli/configuring-npm/package-json
18 - /cli/configuring-npm/package.json
19 - /cli/files/package-json
20 - /cli/files/package.json
21 - /cli/v10/configuring-npm/package.json
22 - /cli/v10/files/package-json
23 - /cli/v10/files/package.json
24 - /configuring-npm/package-json
25 - /configuring-npm/package.json
26 - /files/package-json
27 - /files/package.json
28 ---
29
30 ### Description
31
32 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.
33
34 A lot of the behavior described in this document is affected by the config settings described in [`config`](/cli/v10/using-npm/config).
35
36 ### name
37
38 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.
39
40 The name is what your thing is called.
41
42 Some rules:
43
44 - The name must be less than or equal to 214 characters. This includes the scope for scoped packages.
45 - The names of scoped packages can begin with a dot or an underscore. This is not permitted without a scope.
46 - New packages must not have uppercase letters in the name.
47 - 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.
48
49 Some tips:
50
51 - Don't use the same name as a core Node module.
52 - 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.)
53 - The name will probably be passed as an argument to require(), so it should be something short, but also reasonably descriptive.
54 - 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/](https://www.npmjs.com/)
55
56 A name can be optionally prefixed by a scope, e.g. `@myorg/mypackage`. See [`scope`](/cli/v10/using-npm/scope) for more detail.
57
58 ### version
59
60 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.
61
62 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.)
63
64 ### description
65
66 Put a description in it. It's a string. This helps people discover your package, as it's listed in `npm search`.
67
68 ### keywords
69
70 Put keywords in it. It's an array of strings. This helps people discover your package as it's listed in `npm search`.
71
72 ### homepage
73
74 The URL to the project homepage.
75
76 Example:
77
78 ```json
79 "homepage": "https://github.com/owner/project#readme"
80 ```
81
82 ### bugs
83
84 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.
85
86 It should look like this:
87
88 ```json
89 {
90 "bugs": {
91 "url": "https://github.com/owner/project/issues",
92 "email": "project@hostname.com"
93 }
94 }
95 ```
96
97 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.
98
99 If a URL is provided, it will be used by the `npm bugs` command.
100
101 ### license
102
103 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.
104
105 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:
106
107 ```json
108 {
109 "license": "BSD-3-Clause"
110 }
111 ```
112
113 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.
114
115 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:
116
117 ```json
118 {
119 "license": "(ISC OR GPL-3.0)"
120 }
121 ```
122
123 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:
124
125 ```json
126 {
127 "license": "SEE LICENSE IN <filename>"
128 }
129 ```
130
131 Then include a file named `<filename>` at the top level of the package.
132
133 Some old packages used license objects or a "licenses" property containing an array of license objects:
134
135 ```json
136 // Not valid metadata
137 {
138 "license" : {
139 "type" : "ISC",
140 "url" : "https://opensource.org/licenses/ISC"
141 }
142 }
143
144 // Not valid metadata
145 {
146 "licenses" : [
147 {
148 "type": "MIT",
149 "url": "https://www.opensource.org/licenses/mit-license.php"
150 },
151 {
152 "type": "Apache-2.0",
153 "url": "https://opensource.org/licenses/apache2.0.php"
154 }
155 ]
156 }
157 ```
158
159 Those styles are now deprecated. Instead, use SPDX expressions, like this:
160
161 ```json
162 {
163 "license": "ISC"
164 }
165 ```
166
167 ```json
168 {
169 "license": "(MIT OR Apache-2.0)"
170 }
171 ```
172
173 Finally, if you do not wish to grant others the right to use a private or unpublished package under any terms:
174
175 ```json
176 {
177 "license": "UNLICENSED"
178 }
179 ```
180
181 Consider also setting `"private": true` to prevent accidental publication.
182
183 ### people fields: author, contributors
184
185 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:
186
187 ```json
188 {
189 "name": "Barney Rubble",
190 "email": "b@rubble.com",
191 "url": "http://barnyrubble.tumblr.com/"
192 }
193 ```
194
195 Or you can shorten that all into a single string, and npm will parse it for you:
196
197 ```json
198 {
199 "author": "Barney Rubble <b@rubble.com> (http://barnyrubble.tumblr.com/)"
200 }
201 ```
202
203 Both email and url are optional either way.
204
205 npm also sets a top-level "maintainers" field with your npm user info.
206
207 ### funding
208
209 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:
210
211 ```json
212 {
213 "funding": {
214 "type": "individual",
215 "url": "http://example.com/donate"
216 }
217 }
218 ```
219
220 ```json
221 {
222 "funding": {
223 "type": "patreon",
224 "url": "https://www.patreon.com/my-account"
225 }
226 }
227 ```
228
229 ```json
230 {
231 "funding": "http://example.com/donate"
232 }
233 ```
234
235 ```json
236 {
237 "funding": [
238 {
239 "type": "individual",
240 "url": "http://example.com/donate"
241 },
242 "http://example.com/donateAlso",
243 {
244 "type": "patreon",
245 "url": "https://www.patreon.com/my-account"
246 }
247 ]
248 }
249 ```
250
251 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)
252
253 ### files
254
255 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.
256
257 Some special files and directories are also included or excluded regardless of whether they exist in the `files` array (see below).
258
259 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.
260
261 Certain files are always included, regardless of settings:
262
263 - `package.json`
264 - `README`
265 - `LICENSE` / `LICENCE`
266 - The file in the "main" field
267 - The file(s) in the "bin" field
268
269 `README` & `LICENSE` can have any case and extension.
270
271 Some files are always ignored by default:
272
273 - `*.orig`
274 - `.*.swp`
275 - `.DS_Store`
276 - `._*`
277 - `.git`
278 - `.hg`
279 - `.lock-wscript`
280 - `.npmrc`
281 - `.svn`
282 - `.wafpickle-N`
283 - `CVS`
284 - `config.gypi`
285 - `node_modules`
286 - `npm-debug.log`
287 - `package-lock.json` (use [`npm-shrinkwrap.json`](/cli/v10/configuring-npm/npm-shrinkwrap-json) if you wish it to be published)
288 - `pnpm-lock.yaml`
289 - `yarn.lock`
290
291 Most of these ignored files can be included specifically if included in the `files` globs. Exceptions to this are:
292
293 - `.git`
294 - `.npmrc`
295 - `node_modules`
296 - `package-lock.json`
297 - `pnpm-lock.yaml`
298 - `yarn.lock`
299
300 These can not be included.
301
302 ### exports
303
304 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)
305
306 ### main
307
308 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.
309
310 This should be a module relative to the root of your package folder.
311
312 For most modules, it makes the most sense to have a main script and often not much else.
313
314 If `main` is not set, it defaults to `index.js` in the package's root folder.
315
316 ### browser
317
318 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`)
319
320 ### bin
321
322 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.)
323
324 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`.
325
326 For example, myapp could have this:
327
328 ```json
329 {
330 "bin": {
331 "myapp": "bin/cli.js"
332 }
333 }
334 ```
335
336 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.
337
338 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:
339
340 ```json
341 {
342 "name": "my-program",
343 "version": "1.2.5",
344 "bin": "path/to/program"
345 }
346 ```
347
348 would be the same as this:
349
350 ```json
351 {
352 "name": "my-program",
353 "version": "1.2.5",
354 "bin": {
355 "my-program": "path/to/program"
356 }
357 }
358 ```
359
360 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!
361
362 Note that you can also set the executable files using [directories.bin](#directoriesbin).
363
364 See [folders](/cli/v10/configuring-npm/folders#executables) for more info on executables.
365
366 ### man
367
368 Specify either a single file or an array of filenames to put in place for the `man` program to find.
369
370 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:
371
372 ```json
373 {
374 "name": "foo",
375 "version": "1.2.3",
376 "description": "A packaged foo fooer for fooing foos",
377 "main": "foo.js",
378 "man": "./man/doc.1"
379 }
380 ```
381
382 would link the `./man/doc.1` file in such that it is the target for `man foo`
383
384 If the filename doesn't start with the package name, then it's prefixed. So, this:
385
386 ```json
387 {
388 "name": "foo",
389 "version": "1.2.3",
390 "description": "A packaged foo fooer for fooing foos",
391 "main": "foo.js",
392 "man": ["./man/foo.1", "./man/bar.1"]
393 }
394 ```
395
396 will create files to do `man foo` and `man foo-bar`.
397
398 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.
399
400 ```json
401 {
402 "name": "foo",
403 "version": "1.2.3",
404 "description": "A packaged foo fooer for fooing foos",
405 "main": "foo.js",
406 "man": ["./man/foo.1", "./man/foo.2"]
407 }
408 ```
409
410 will create entries for `man foo` and `man 2 foo`
411
412 ### directories
413
414 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.
415
416 In the future, this information may be used in other creative ways.
417
418 #### directories.bin
419
420 If you specify a `bin` directory in `directories.bin`, all the files in that folder will be added.
421
422 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`.
423
424 #### directories.man
425
426 A folder that is full of man pages. Sugar to generate a "man" array by walking the folder.
427
428 ### repository
429
430 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.
431
432 Do it like this:
433
434 ```json
435 {
436 "repository": {
437 "type": "git",
438 "url": "git+https://github.com/npm/cli.git"
439 }
440 }
441 ```
442
443 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.
444
445 For GitHub, GitHub gist, Bitbucket, or GitLab repositories you can use the same shortcut syntax you use for `npm install`:
446
447 ```json
448 {
449 "repository": "npm/npm",
450
451 "repository": "github:user/repo",
452
453 "repository": "gist:11081aaa281",
454
455 "repository": "bitbucket:user/repo",
456
457 "repository": "gitlab:user/repo"
458 }
459 ```
460
461 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:
462
463 ```json
464 {
465 "repository": {
466 "type": "git",
467 "url": "git+https://github.com/npm/cli.git",
468 "directory": "workspaces/libnpmpublish"
469 }
470 }
471 ```
472
473 ### scripts
474
475 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.
476
477 See [`scripts`](/cli/v10/using-npm/scripts) to find out more about writing package scripts.
478
479 ### config
480
481 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:
482
483 ```json
484 {
485 "name": "foo",
486 "config": {
487 "port": "8080"
488 }
489 }
490 ```
491
492 It could also have a "start" command that referenced the `npm_package_config_port` environment variable.
493
494 ### dependencies
495
496 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.
497
498 **Please do not put test harnesses or transpilers or other "development" time tools in your `dependencies` object.** See `devDependencies`, below.
499
500 See [semver](https://github.com/npm/node-semver#versions) for more details about specifying version ranges.
501
502 - `version` Must match `version` exactly
503 - `>version` Must be greater than `version`
504 - `>=version` etc
505 - `<version`
506 - `<=version`
507 - `~version` "Approximately equivalent to version" See [semver](https://github.com/npm/node-semver#versions)
508 - `^version` "Compatible with version" See [semver](https://github.com/npm/node-semver#versions)
509 - `1.2.x` 1.2.0, 1.2.1, etc., but not 1.3.0
510 - `http://...` See 'URLs as Dependencies' below
511 - `*` Matches any version
512 - `""` (just an empty string) Same as `*`
513 - `version1 - version2` Same as `>=version1 <=version2`.
514 - `range1 || range2` Passes if either range1 or range2 are satisfied.
515 - `git...` See 'Git URLs as Dependencies' below
516 - `user/repo` See 'GitHub URLs' below
517 - `tag` A specific version tagged and published as `tag` See [`npm dist-tag`](/cli/v10/commands/npm-dist-tag)
518 - `path/path/path` See [Local Paths](#local-paths) below
519 - `npm:@scope/pkg@version` Custom alias for a pacakge See [`package-spec`](/cli/v10/using-npm/package-spec#aliases)
520
521 For example, these are all valid:
522
523 ```json
524 {
525 "dependencies": {
526 "foo": "1.0.0 - 2.9999.9999",
527 "bar": ">=1.0.2 <2.1.2",
528 "baz": ">1.0.2 <=2.3.4",
529 "boo": "2.0.1",
530 "qux": "<1.0.0 || >=2.3.1 <2.4.5 || >=2.5.2 <3.0.0",
531 "asd": "http://asdf.com/asdf.tar.gz",
532 "til": "~1.2",
533 "elf": "~1.2.3",
534 "two": "2.x",
535 "thr": "3.3.x",
536 "lat": "latest",
537 "dyl": "file:../dyl",
538 "kpg": "npm:pkg@1.0.0"
539 }
540 }
541 ```
542
543 #### URLs as Dependencies
544
545 You may specify a tarball URL in place of a version range.
546
547 This tarball will be downloaded and installed locally to your package at install time.
548
549 #### Git URLs as Dependencies
550
551 Git URLs are of the form:
552
553 ```bash
554 <protocol>://[<user>[:<password>]@]<hostname>[:<port>][:][/]<path>[#<commit-ish> | #semver:<semver>]
555 ```
556
557 `<protocol>` is one of `git`, `git+ssh`, `git+http`, `git+https`, or `git+file`.
558
559 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.
560
561 Examples:
562
563 ```bash
564 git+ssh://git@github.com:npm/cli.git#v1.0.27
565 git+ssh://git@github.com:npm/cli#semver:^5.0
566 git+https://isaacs@github.com/npm/cli.git
567 git://github.com/npm/cli.git#v1.0.27
568 ```
569
570 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.
571
572 This flow will occur if your git dependency uses `workspaces`, or if any of the following scripts are present:
573
574 - `build`
575 - `prepare`
576 - `prepack`
577 - `preinstall`
578 - `install`
579 - `postinstall`
580
581 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.
582
583 #### GitHub URLs
584
585 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:
586
587 ```json
588 {
589 "name": "foo",
590 "version": "0.0.0",
591 "dependencies": {
592 "express": "expressjs/express",
593 "mocha": "mochajs/mocha#4727d357ea",
594 "module": "user/repo#feature/branch"
595 }
596 }
597 ```
598
599 #### Local Paths
600
601 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:
602
603 ```bash
604 ../foo/bar
605 ~/foo/bar
606 ./foo/bar
607 /foo/bar
608 ```
609
610 in which case they will be normalized to a relative path and added to your `package.json`. For example:
611
612 ```json
613 {
614 "name": "baz",
615 "dependencies": {
616 "bar": "file:../foo/bar"
617 }
618 }
619 ```
620
621 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.
622
623 _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.
624
625 ### devDependencies
626
627 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.
628
629 In this case, it's best to map these additional items in a `devDependencies` object.
630
631 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 [`config`](/cli/v10/using-npm/config) for more on the topic.
632
633 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.
634
635 For example:
636
637 ```json
638 {
639 "name": "ethopia-waza",
640 "description": "a delightfully fruity coffee varietal",
641 "version": "1.2.3",
642 "devDependencies": {
643 "coffee-script": "~1.6.3"
644 },
645 "scripts": {
646 "prepare": "coffee -o lib/ -c src/waza.coffee"
647 },
648 "main": "lib/waza.js"
649 }
650 ```
651
652 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.
653
654 ### peerDependencies
655
656 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.
657
658 For example:
659
660 ```json
661 {
662 "name": "tea-latte",
663 "version": "1.3.5",
664 "peerDependencies": {
665 "tea": "2.x"
666 }
667 }
668 ```
669
670 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:
671
672 ```bash
673 ├── tea-latte@1.3.5
674 └── tea@2.2.0
675 ```
676
677 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.
678
679 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.
680
681 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"`.
682
683 ### peerDependenciesMeta
684
685 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.
686
687 For example:
688
689 ```json
690 {
691 "name": "tea-latte",
692 "version": "1.3.5",
693 "peerDependencies": {
694 "tea": "2.x",
695 "soy-milk": "1.2"
696 },
697 "peerDependenciesMeta": {
698 "soy-milk": {
699 "optional": true
700 }
701 }
702 }
703 ```
704
705 ### bundleDependencies
706
707 This defines an array of package names that will be bundled when publishing the package.
708
709 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`.
710
711 For example:
712
713 If we define a package.json like this:
714
715 ```json
716 {
717 "name": "awesome-web-framework",
718 "version": "1.0.0",
719 "bundleDependencies": ["renderized", "super-streams"]
720 }
721 ```
722
723 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`.
724
725 If this is spelled `"bundledDependencies"`, then that is also honored.
726
727 Alternatively, `"bundleDependencies"` can be defined as a boolean value. A value of `true` will bundle all dependencies, a value of `false` will bundle none.
728
729 ### optionalDependencies
730
731 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.
732
733 It is still your program's responsibility to handle the lack of the dependency. For example, something like this:
734
735 ```js
736 try {
737 var foo = require("foo");
738 var fooVersion = require("foo/package.json").version;
739 } catch (er) {
740 foo = null;
741 }
742 if (notGoodFooVersion(fooVersion)) {
743 foo = null;
744 }
745
746 // .. then later in your program ..
747
748 if (foo) {
749 foo.doFooThings();
750 }
751 ```
752
753 Entries in `optionalDependencies` will override entries of the same name in `dependencies`, so it's usually best to only put in one place.
754
755 ### overrides
756
757 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.
758
759 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.
760
761 Overrides are only considered in the root `package.json` file for a project. Overrides in installed dependencies (including [workspaces](/cli/v10/using-npm/workspaces)) are not considered in dependency tree resolution. Published packages may dictate their resolutions by pinning dependencies or using an [`npm-shrinkwrap.json`](/cli/v10/configuring-npm/npm-shrinkwrap-json) file.
762
763 To make sure the package `foo` is always installed as version `1.0.0` no matter what version your dependencies rely on:
764
765 ```json
766 {
767 "overrides": {
768 "foo": "1.0.0"
769 }
770 }
771 ```
772
773 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`:
774
775 ```json
776 {
777 "overrides": {
778 "foo": {
779 ".": "1.0.0",
780 "bar": "1.0.0"
781 }
782 }
783 }
784 ```
785
786 To only override `foo` to be `1.0.0` when it's a child (or grandchild, or great grandchild, etc) of the package `bar`:
787
788 ```json
789 {
790 "overrides": {
791 "bar": {
792 "foo": "1.0.0"
793 }
794 }
795 }
796 ```
797
798 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`:
799
800 ```json
801 {
802 "overrides": {
803 "baz": {
804 "bar": {
805 "foo": "1.0.0"
806 }
807 }
808 }
809 }
810 ```
811
812 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`:
813
814 ```json
815 {
816 "overrides": {
817 "bar@2.0.0": {
818 "foo": "1.0.0"
819 }
820 }
821 }
822 ```
823
824 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 `$`.
825
826 ```json
827 {
828 "dependencies": {
829 "foo": "^1.0.0"
830 },
831 "overrides": {
832 // BAD, will throw an EOVERRIDE error
833 // "foo": "^2.0.0"
834 // GOOD, specs match so override is allowed
835 // "foo": "^1.0.0"
836 // BEST, the override is defined as a reference to the dependency
837 "foo": "$foo",
838 // the referenced package does not need to match the overridden one
839 "bar": "$foo"
840 }
841 }
842 ```
843
844 ### engines
845
846 You can specify the version of node that your stuff works on:
847
848 ```json
849 {
850 "engines": {
851 "node": ">=0.10.3 <15"
852 }
853 }
854 ```
855
856 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.
857
858 You can also use the "engines" field to specify which versions of npm are capable of properly installing your program. For example:
859
860 ```json
861 {
862 "engines": {
863 "npm": "~1.0.20"
864 }
865 }
866 ```
867
868 Unless the user has set the [`engine-strict` config](/cli/v10/using-npm/config#engine-strict) flag, this field is advisory only and will only produce warnings when your package is installed as a dependency.
869
870 ### os
871
872 You can specify which operating systems your module will run on:
873
874 ```json
875 {
876 "os": ["darwin", "linux"]
877 }
878 ```
879
880 You can also block instead of allowing operating systems, just prepend the blocked os with a '!':
881
882 ```json
883 {
884 "os": ["!win32"]
885 }
886 ```
887
888 The host operating system is determined by `process.platform`
889
890 It is allowed to both block and allow an item, although there isn't any good reason to do this.
891
892 ### cpu
893
894 If your code only runs on certain cpu architectures, you can specify which ones.
895
896 ```json
897 {
898 "cpu": ["x64", "ia32"]
899 }
900 ```
901
902 Like the `os` option, you can also block architectures:
903
904 ```json
905 {
906 "cpu": ["!arm", "!mips"]
907 }
908 ```
909
910 The host architecture is determined by `process.arch`
911
912 ### devEngines
913
914 The `devEngines` field aids engineers working on a codebase to all be using the same tooling.
915
916 You can specify a `devEngines` property in your `package.json` which will run before `install`, `ci`, and `run` commands.
917
918 > 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.
919
920 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.
921
922 ```json
923 {
924 "devEngines": {
925 "runtime": {
926 "name": "node",
927 "onFail": "error"
928 },
929 "packageManager": {
930 "name": "npm",
931 "onFail": "error"
932 }
933 }
934 }
935 ```
936
937 ### private
938
939 If you set `"private": true` in your package.json, then npm will refuse to publish it.
940
941 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.
942
943 ### publishConfig
944
945 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.
946
947 See [`config`](/cli/v10/using-npm/config) to see the list of config options that can be overridden.
948
949 ### workspaces
950
951 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 [workspace](/cli/v10/using-npm/workspaces) that needs to be symlinked to the top level `node_modules` folder.
952
953 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.
954
955 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:
956
957 ```json
958 {
959 "name": "workspace-example",
960 "workspaces": ["./packages/*"]
961 }
962 ```
963
964 See [`workspaces`](/cli/v10/using-npm/workspaces) for more examples.
965
966 ### DEFAULT VALUES
967
968 npm will default some values based on package contents.
969
970 - `"scripts": {"start": "node server.js"}`
971
972 If there is a `server.js` file in the root of your package, then npm will default the `start` command to `node server.js`.
973
974 - `"scripts":{"install": "node-gyp rebuild"}`
975
976 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.
977
978 - `"contributors": [...]`
979
980 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.
981
982 ### SEE ALSO
983
984 - [semver](https://github.com/npm/node-semver#versions)
985 - [workspaces](/cli/v10/using-npm/workspaces)
986 - [npm init](/cli/v10/commands/npm-init)
987 - [npm version](/cli/v10/commands/npm-version)
988 - [npm config](/cli/v10/commands/npm-config)
989 - [npm help](/cli/v10/commands/npm-help)
990 - [npm install](/cli/v10/commands/npm-install)
991 - [npm publish](/cli/v10/commands/npm-publish)
992 - [npm uninstall](/cli/v10/commands/npm-uninstall)