joshuakgoldberg/js

This repository houses the core JavaScript language tools that power ESLint, one of the most popular tools developers use to catch mistakes and enforce consistent code style. The three packages here don't check rules themselves, they handle the foundational work of reading JavaScript code and understanding its structure so that rule-checking tools can do their jobs. The three packages split that job into stages. Espree takes raw JavaScript source code and turns it into a structured tree representation that programs can analyze. Eslint-visitor-keys provides the map of what parts of that tree exist and how they connect, so tools can walk through the code systematically. Eslint-scope figures out where variables are defined and where they're used, which is essential for detecting things like unused variables or references to things that don't exist. Together, they form a pipeline that turns text into something a machine can reason about. The primary audience is developers building or maintaining linting tools, code editors, or other tooling that needs to analyze JavaScript. If you're building a custom ESLint rule, a code transformation tool, or an editor extension that highlights problems in JavaScript files, these packages do the heavy lifting of parsing and scoping so you don't have to write a JavaScript parser from scratch. Beyond what the package list tells us, the README doesn't go into further detail on usage or architecture. It does note a strong security posture and backing from major sponsors like Airbnb, Automattic, and Shopify, which signals that these are widely used, production-grade dependencies rather than experimental projects.