yarn

The JavaScript ecosystem has never had a single package manager. For years, npm was the default—it shipped with Node.js, and it worked. But in 2016, Yarn arrived with a promise of speed, determinism, and better dependency management. Nearly a decade later, the landscape is more complicated: Yarn has evolved through multiple major versions, npm has…

Installing Yarn used to mean a single global command. That era is over. Modern Yarn—versions 2, 3, and 4, collectively called “Berry”—is designed to be installed per-project, not globally. The tool that makes this possible is Corepack, a Node.js utility that intercepts yarn commands and routes them to the exact version declared in your project’s…

Every Yarn project begins with a single file. Before dependencies are installed, before scripts are run, and before lockfiles are generated, there is package.json. This file is the manifest—the contract between your project, the package manager, and anyone who clones the repository. Running yarn init is the first command in any new project, and understanding…

Every dependency you add, upgrade, or remove triggers a two-file update: package.json records the intent (a version range like ^4.18.0), and yarn.lock records the reality (the exact version and integrity hash that was resolved). The manifest is what you write; the lockfile is what Yarn writes. Understanding this division is the difference between a project…

Package management is the daily rhythm of working with Yarn. You add a library to solve a problem, upgrade it when a bug is fixed or a feature lands, and remove it when the dependency is no longer needed. Each of these operations modifies two files—package.json and yarn.lock—and the commands that perform them differ significantly…

A project’s package.json is not just a dependency manifest. It is also a command registry. The scripts field defines named commands that can be invoked with a short alias, and Yarn provides a resolution layer that decides whether a given name refers to a script, a taskfile, or a binary from a dependency. In Yarn…

A monorepo stores multiple packages in a single repository. Yarn Workspaces is the mechanism that makes this practical: it installs all packages’ dependencies together, links packages to each other without publishing to a registry, and provides commands to run scripts across the entire project. In Yarn Berry (2+), the feature set expands significantly with the…

Every package manager before Yarn PnP relied on the same fundamental mechanism: placing files into a node_modules directory and letting Node.js walk up the directory tree to find them. Yarn Plug’n’Play discards this model entirely. Instead of copying packages into a folder tree, PnP generates a single loader file—.pnp.cjs—that contains a complete map of the…

Zero-Installs is a Yarn pattern that eliminates the need to run yarn install after cloning a repository or switching branches. It works by committing the install artifacts—the PnP loader files and the project-local package cache—directly to version control. The result is a repository that is immediately runnable on checkout, with no network requests and no…

The .yarnrc.yml file is the central configuration hub for Yarn Berry (2+). Every project-level setting—how packages are linked, where the cache lives, which registry is queried, how workspaces behave—lives in this single YAML file. Unlike package.json, which is shared with npm and the broader Node.js ecosystem, .yarnrc.yml is Yarn-specific and is the only file that…