Training Example: Yarn – Review the Data, Give Your Score & Compare to the Real AI Evaluation

[H1] Safe, stable,reproducible projectsstable... canary...
Yarn is a package manager that doubles down as project manager. Whether you work on simple projects or industry monorepos, whether you're an open source developer or an enterprise user, Yarn has your back.This documentation covers Yarn 4+. For the previous documentation dedicated to 3.6 and below, please refer to v3.yarnpkg.com.
[H3] Workspaces
First package manager built specifically around workspaces, Yarn lets you split your project into sub-components.
[H3] Stability
Yarn guarantees that installs that work today will keep working the same way in the future.
[H3] Documentation
Special care is put into our documentation, which we keep improving at every new version.
[H3] Plugins
Yarn may not solve all your problems - but it'll give you the tools to solve the ones you find on your way.
[H3] Innovation
We believe in challenging the status quo. Yarn will always be at the frontline, brewing new workflows and improving old ones.
[H3] Openness
Yarn is a fully independent open-source project tied to no company. Our contributor community defines the roadmap.

Yarn is an established open-source package manager used to manage dependencies in JavaScript projects. It assists with the process of installing, updating, configuring, and removing packages dependencies, eventually helping you reach your objectives faster with fewer distractions.
Its areas of focus are speed, correctness, security, and developer experience, which we improve along every axis by leveraging a suite of innovative features such as workspaces, offline caching, parallel installs, hardened mode, interactive commands, and more.
Given its robust features and stellar track record, Yarn proves to be an indispensable asset to the JavaScript ecosystem, driving efficiency, security, and positive developer experience in projects of any size.
infoUnlike most other package managers, which typically defer to npm for non-install-related commands, Yarn reimplements all commands, so as to have full control over our developer experience and stability.

On this page
[H2] Overview​
Yarn boasts a wide set of cache settings, letting you tweak depending on your preferred workflows or CI platforms. This documentation goes over some of the most interesting patterns to know.
tipYarn will by default cache everything you install and mutualize them for all other projects on your machine; this improves both installation speed and disk footprint, just like if you were using hardlinks.
[H2] Major patterns​
[H3] Offline mirror​
When installed for the first time on a machine, packages are usually retrieved from the npm registry. While it usually works fine, it's not always the case - the registry is known to experience issues from time to time that often result in failed installs. If you're not prepared, it may be a significant disruption for your developers, as switching branches and performing deploys can be much harder or unstable.
Some companies try to avoid this problem by configuring their registry to a mirror they control (for example by having a server run Verdaccio, an open-source implementation of the npm registry). It however requires a specific setup that isn't always easy to deploy to both developers and CI, and those systems sometimes come with risks.
Yarn provides a very simple but effective alternative: by setting enableGlobalCache to false, it will save the package cache into a folder local to your project (by default .yarn/cache) that can then be added to Git. Every given commit is thus guaranteed to be installable, even should the npm registry go under.
[H3] Zero-installs​
Zero-installs are the combination of two Yarn features that allow you to skip having to think about running yarn install when switching branches - a requirement otherwise easy to forget until you see your tools crash.
As we saw, the offline mirror removes your project's dependency on the npm registry by keeping the Yarn cache within the repository. But can we go further, and directly make this cache the actual? The answer is yes!
As long as your project uses Yarn PnP and the offline mirror, all you have to do is add the loader files to Git, and you can forget yarn install most of the time. Since the PnP loaders have exactly the same content regardless of the machine that generated them, and since the offline cache will contain all the files that the loaders reference, the git checkout calls effectively double as yarn install of sort.
One caveat: adding or removing packages with native dependencies will still require yarn install to be run, as such packages depend on files that, unlike Node.js scripts, can't be evaluated directly from within their zip archives. Those packages are quite rare in practice, aren't frequently updated, and Yarn will display an helpful error message should you forget to do it, so this doesn't significantly impact the usefulness of the pattern.
infoZero-installs are technically possible by adding your node_modules folders to Git. The difference however is that node_modules folders contain multiple thousands of files that Git each has to diff individually, that the hoisting causes them to frequently be moved around, and that people have a bad tendency to make manual changes to their node_modules folder that end up committed.By contrast, adding your cache to Git and using Yarn PnP gives you a single folder with exactly one zip archive for each package, plus the PnP loader file. This is vastly easier for Git to track, as we saw earlier.
[H2] Specific environments​
[H3] GitHub Actions​
infoWe're still investigating the exact set of defaults that make GH Action caching more efficient. It's likely that we'll provide an official yarn-cache action mid-term for this purpose.OverviewMajor patternsOffline mirrorZero-installsSpecific environmentsGitHub Actions

On this page
[H2] General commands​
yarn addAdd dependencies to the project.yarn binGet the path to a binary script.yarn cache cleanRemove the shared cache files.yarn configDisplay the current configuration.yarn config getRead a configuration settings.yarn config setChange a configuration settings.yarn config unsetUnset a configuration setting.yarn dedupeDeduplicate dependencies with overlapping ranges.yarn dlxRun a package in a temporary environment.yarn execExecute a shell script.yarn explainExplain an error code.yarn explain peer-requirementsExplain a set of peer requirements.yarn infoSee information related to packages.yarn initCreate a new package.yarn initCreate a new package.yarn installInstall the project dependencies.yarn linkConnect the local project to another one.yarn nodeRun node with the hook already setup.yarn npm auditPerform a vulnerability audit against the installed packages.yarn packGenerate a tarball from the active workspace.yarn patchPrepare a package for patching.yarn patch-commitGenerate a patch out of a directory.yarn rebuildRebuild the project's native packages.yarn removeRemove dependencies from the project.yarn runRun a script defined in the package.json.yarn set resolutionEnforce a package resolution.yarn set versionLock the Yarn version used by the project.yarn set version from sourcesBuild Yarn from master.yarn stageAdd all yarn files to your vcs.yarn unlinkDisconnect the local project from another one.yarn unplugForce the unpacking of a list of packages.yarn upUpgrade dependencies across the project.yarn whyDisplay the reason why a package is needed.
[H2] Constraints-related commands​
yarn constraintsCheck that the project constraints are met.yarn constraints queryQuery the constraints fact database.yarn constraints sourcePrint the source code for the constraints.
[H2] Npm-related commands​
yarn npm infoShow information about a package.yarn npm loginStore new login info to access the npm registry.yarn npm logoutLogout of the npm registry.yarn npm publishPublish the active workspace to the npm registry.yarn npm stage approveApprove a staged package version for publishing.yarn npm stage listList all staged package versions.yarn npm stage rejectReject a staged package version.yarn npm tag addAdd a tag for a specific version of a package.yarn npm tag listList all dist-tags of a package.yarn npm tag removeRemove a tag from a package.yarn npm whoamiDisplay the name of the authenticated user.
[H2] Plugin-related commands​
yarn plugin checkFind all third-party plugins that differ from their own spec.yarn plugin importDownload a plugin.yarn plugin import from sourcesBuild a plugin from sources.yarn plugin listList the available official plugins.yarn plugin removeRemove a plugin.yarn plugin runtimeList the active plugins.
[H2] Interactive commands​
yarn searchOpen the search interface.yarn upgrade-interactiveOpen the upgrade interface.
[H2] Release-related commands​
yarn versionApply a new version to the current package.yarn version applyApply all the deferred version bumps at once.yarn version checkCheck that all the relevant packages have been bumped.
[H2] Workspace-related commands​
yarn workspaceRun a command within the specified workspace.yarn workspaces focusInstall a single workspace and its dependencies.yarn workspaces foreachRun a command on all workspaces.yarn workspaces listList all available workspaces.General commandsConstraints-related commandsNpm-related commandsPlugin-related commandsInteractive commandsRelease-related commandsWorkspace-related commands