ESLint v10 is flat-config only. The .eslintrc system is gone, the config resolution starts from each file’s directory, and the Node.js floor is ^20.19.0 || ^22.13.0 || >=24 . The cheatsheet is the set of decisions that keep a v10 config loadable and a rule set predictable. The Node.js Gate Version Status ^20.19.0 Supported ^22.13.0…
ESLint v10.0.0 was released on February 5, 2026, and it is the release that completes the flat config migration that began in v9. The legacy .eslintrc system is gone entirely, the Node.js support window has moved forward, and several core rules have changed their defaults or their schemas in ways that will surface new lint…
A custom ESLint rule is a module that exports an object with two properties: meta and create. The meta property describes the rule—its type, its documentation, its options schema, and its message templates. The create method receives the rule context and returns a visitor object whose keys are AST node types or selectors, and whose…
Prettier 3.x is ESM-first, async, and plugin-driven. The config file resolution searches upward from the file being formatted, and the first config found wins. The CLI flags map to the API options, and the plugins are the extension surface for languages and sorting. The CLI Commands Command Purpose prettier . Format to stdout (no write)…
A monorepo’s Prettier configuration has two layers: the shared config that every package should inherit, and the per-package overrides that a specific package needs. The mechanism is Prettier’s configuration file resolution, which searches upward from the file being formatted until it finds a config. A package-level config stops the search, so the shared config at…
Prettier 3.0 was released on July 5, 2023, and it was the first major version to make the entire codebase ECMAScript Modules. The migration was not a cosmetic change. It affected how the library is loaded, how plugins are written, and how the API is called. The three breaking changes that matter most for a…
Prettier does not sort imports. It formats the imports that exist, but it leaves their order exactly as written. The sorting is a separate concern, and it is provided by plugins. The three that matter are @trivago/prettier-plugin-sort-imports, which is the original regex-based sorter, @ianvs/prettier-plugin-sort-imports, which is a fork of the original with safer defaults, and…
The prettier-plugin-tailwindcss plugin does one thing: it sorts Tailwind CSS classes in the order that Tailwind’s own tooling recommends. It is not a linter, and it does not detect unused or conflicting classes. It reads the class strings in your markup—the class attribute, the framework-specific equivalents like className, and the function calls you configure—and rewrites…
This cheatsheet covers Parcel 2.x, the current stable line. It is scoped to the decisions you make mid-build: the CLI commands, the package.json targets, the .parcelrc plugin configuration, the transformer pipelines, and the deployment settings. The shape of Parcel 2 is the plugin pipeline, and the cheatsheet is the set of hooks and conventions that…
Parcel produces a static bundle. The parcel build command reads the entry file—usually an index.html—and writes the optimized output to the dist directory. The deployment is the process of serving that dist directory from a static host, and the server configuration is the set of rules that tells the host how to serve the files:…