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ESLint

A pluggable linter for JavaScript and TypeScript.

ESLint analyses JavaScript and TypeScript code statically and reports problems against a configurable rule set. Rules can range from simple stylistic checks (semicolons, indentation) to deep correctness analysis (no-unused-vars, no-floating-promises, no-implicit-globals). Configurations are composable: many teams extend a base ruleset (Airbnb's, Standard, eslint-config-react) and override individual rules to taste.

Nicholas C. Zakas created ESLint in 2013 as a more pluggable alternative to JSHint and JSLint. The project moved under the OpenJS Foundation in 2019 and is funded by sponsorships from companies that depend on it. ESLint has gone through several major configuration system overhauls; the current "flat config" format unifies what used to be three or four different ways of expressing rules and overrides.

ESLint is one of the most widely deployed JavaScript tools in existence — virtually every modern frontend or Node.js project runs it as part of its build or pre-commit checks. The typescript-eslint sister project extends the same rule infrastructure to TypeScript, with type-aware rules that require running the TypeScript compiler.

npm install --save-dev eslint
Or globally: npm install -g eslint