239 lines
10 KiB
Markdown
239 lines
10 KiB
Markdown
---
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title: package-lock.json
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section: 5
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description: A manifestation of the manifest
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---
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### Description
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`package-lock.json` is automatically generated for any operations where npm
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modifies either the `node_modules` tree, or `package.json`. It describes the
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exact tree that was generated, such that subsequent installs are able to
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generate identical trees, regardless of intermediate dependency updates.
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This file is intended to be committed into source repositories, and serves
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various purposes:
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* Describe a single representation of a dependency tree such that
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teammates, deployments, and continuous integration are guaranteed to
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install exactly the same dependencies.
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* Provide a facility for users to "time-travel" to previous states of
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`node_modules` without having to commit the directory itself.
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* Facilitate greater visibility of tree changes through readable source
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control diffs.
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* Optimize the installation process by allowing npm to skip repeated
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metadata resolutions for previously-installed packages.
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* As of npm v7, lockfiles include enough information to gain a complete
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picture of the package tree, reducing the need to read `package.json`
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files, and allowing for significant performance improvements.
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### `package-lock.json` vs `npm-shrinkwrap.json`
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Both of these files have the same format, and perform similar functions in
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the root of a project.
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The difference is that `package-lock.json` cannot be published, and it will
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be ignored if found in any place other than the root project.
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In contrast, [npm-shrinkwrap.json](/configuring-npm/npm-shrinkwrap-json) allows
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publication, and defines the dependency tree from the point encountered.
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This is not recommended unless deploying a CLI tool or otherwise using the
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publication process for producing production packages.
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If both `package-lock.json` and `npm-shrinkwrap.json` are present in the
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root of a project, `npm-shrinkwrap.json` will take precedence and
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`package-lock.json` will be ignored.
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### Hidden Lockfiles
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In order to avoid processing the `node_modules` folder repeatedly, npm as
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of v7 uses a "hidden" lockfile present in
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`node_modules/.package-lock.json`. This contains information about the
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tree, and is used in lieu of reading the entire `node_modules` hierarchy
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provided that the following conditions are met:
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- All package folders it references exist in the `node_modules` hierarchy.
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- No package folders exist in the `node_modules` hierarchy that are not
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listed in the lockfile.
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- The modified time of the file is at least as recent as all of the package
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folders it references.
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That is, the hidden lockfile will only be relevant if it was created as
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part of the most recent update to the package tree. If another CLI mutates
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the tree in any way, this will be detected, and the hidden lockfile will be
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ignored.
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Note that it _is_ possible to manually change the _contents_ of a package
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in such a way that the modified time of the package folder is unaffected.
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For example, if you add a file to `node_modules/foo/lib/bar.js`, then the
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modified time on `node_modules/foo` will not reflect this change. If you
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are manually editing files in `node_modules`, it is generally best to
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delete the file at `node_modules/.package-lock.json`.
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As the hidden lockfile is ignored by older npm versions, it does not
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contain the backwards compatibility affordances present in "normal"
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lockfiles. That is, it is `lockfileVersion: 3`, rather than
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`lockfileVersion: 2`.
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### Handling Old Lockfiles
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When npm detects a lockfile from npm v6 or before during the package
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installation process, it is automatically updated to fetch missing
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information from either the `node_modules` tree or (in the case of empty
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`node_modules` trees or very old lockfile formats) the npm registry.
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### File Format
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#### `name`
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The name of the package this is a package-lock for. This will match what's
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in `package.json`.
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#### `version`
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The version of the package this is a package-lock for. This will match
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what's in `package.json`.
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#### `lockfileVersion`
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An integer version, starting at `1` with the version number of this
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document whose semantics were used when generating this
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`package-lock.json`.
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Note that the file format changed significantly in npm v7 to track
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information that would have otherwise required looking in `node_modules` or
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the npm registry. Lockfiles generated by npm v7 will contain
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`lockfileVersion: 2`.
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* No version provided: an "ancient" shrinkwrap file from a version of npm
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prior to npm v5.
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* `1`: The lockfile version used by npm v5 and v6.
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* `2`: The lockfile version used by npm v7, which is backwards compatible
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to v1 lockfiles.
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* `3`: The lockfile version used by npm v7, _without_ backwards
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compatibility affordances. This is used for the hidden lockfile at
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`node_modules/.package-lock.json`, and will likely be used in a future
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version of npm, once support for npm v6 is no longer relevant.
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npm will always attempt to get whatever data it can out of a lockfile, even
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if it is not a version that it was designed to support.
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#### `packages`
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This is an object that maps package locations to an object containing the
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information about that package.
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The root project is typically listed with a key of `""`, and all other
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packages are listed with their relative paths from the root project folder.
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Package descriptors have the following fields:
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* version: The version found in `package.json`
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* resolved: The place where the package was actually resolved from. In
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the case of packages fetched from the registry, this will be a url to a
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tarball. In the case of git dependencies, this will be the full git url
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with commit sha. In the case of link dependencies, this will be the
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location of the link target. `registry.npmjs.org` is a magic value meaning
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"the currently configured registry".
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* integrity: A `sha512` or `sha1` [Standard Subresource
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Integrity](https://w3c.github.io/webappsec/specs/subresourceintegrity/)
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string for the artifact that was unpacked in this location.
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* link: A flag to indicate that this is a symbolic link. If this is
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present, no other fields are specified, since the link target will also
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be included in the lockfile.
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* dev, optional, devOptional: If the package is strictly part of the
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`devDependencies` tree, then `dev` will be true. If it is strictly part
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of the `optionalDependencies` tree, then `optional` will be set. If it
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is both a `dev` dependency _and_ an `optional` dependency of a non-dev
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dependency, then `devOptional` will be set. (An `optional` dependency of
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a `dev` dependency will have both `dev` and `optional` set.)
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* inBundle: A flag to indicate that the package is a bundled dependency.
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* hasInstallScript: A flag to indicate that the package has a `preinstall`,
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`install`, or `postinstall` script.
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* hasShrinkwrap: A flag to indicate that the package has an
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`npm-shrinkwrap.json` file.
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* bin, license, engines, dependencies, optionalDependencies: fields from
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`package.json`
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#### dependencies
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Legacy data for supporting versions of npm that use `lockfileVersion: 1`.
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This is a mapping of package names to dependency objects. Because the
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object structure is strictly hierarchical, symbolic link dependencies are
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somewhat challenging to represent in some cases.
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npm v7 ignores this section entirely if a `packages` section is present,
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but does keep it up to date in order to support switching between npm v6
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and npm v7.
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Dependency objects have the following fields:
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* version: a specifier that varies depending on the nature of the package,
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and is usable in fetching a new copy of it.
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* bundled dependencies: Regardless of source, this is a version number
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that is purely for informational purposes.
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* registry sources: This is a version number. (eg, `1.2.3`)
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* git sources: This is a git specifier with resolved committish. (eg,
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`git+https://example.com/foo/bar#115311855adb0789a0466714ed48a1499ffea97e`)
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* http tarball sources: This is the URL of the tarball. (eg,
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`https://example.com/example-1.3.0.tgz`)
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* local tarball sources: This is the file URL of the tarball. (eg
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`file:///opt/storage/example-1.3.0.tgz`)
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* local link sources: This is the file URL of the link. (eg
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`file:libs/our-module`)
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* integrity: A `sha512` or `sha1` [Standard Subresource
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Integrity](https://w3c.github.io/webappsec/specs/subresourceintegrity/)
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string for the artifact that was unpacked in this location. For git
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dependencies, this is the commit sha.
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* resolved: For registry sources this is path of the tarball relative to
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the registry URL. If the tarball URL isn't on the same server as the
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registry URL then this is a complete URL. `registry.npmjs.org` is a magic
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value meaning "the currently configured registry".
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* bundled: If true, this is the bundled dependency and will be installed
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by the parent module. When installing, this module will be extracted
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from the parent module during the extract phase, not installed as a
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separate dependency.
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* dev: If true then this dependency is either a development dependency ONLY
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of the top level module or a transitive dependency of one. This is false
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for dependencies that are both a development dependency of the top level
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and a transitive dependency of a non-development dependency of the top
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level.
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* optional: If true then this dependency is either an optional dependency
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ONLY of the top level module or a transitive dependency of one. This is
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false for dependencies that are both an optional dependency of the top
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level and a transitive dependency of a non-optional dependency of the top
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level.
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* requires: This is a mapping of module name to version. This is a list of
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everything this module requires, regardless of where it will be
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installed. The version should match via normal matching rules a
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dependency either in our `dependencies` or in a level higher than us.
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* dependencies: The dependencies of this dependency, exactly as at the top
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level.
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### See also
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* [npm shrinkwrap](/commands/npm-shrinkwrap)
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* [npm-shrinkwrap.json](/configuring-npm/npm-shrinkwrap-json)
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* [package.json](/configuring-npm/package-json)
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* [npm install](/commands/npm-install)
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