JSLint: A Beginner’s Guide to Catching JavaScript Errors Early

JSLint vs ESLint: Which JavaScript Linter Should You Use?JavaScript linters help teams catch errors, enforce coding style, and keep codebases consistent. Two well-known tools in the space are JSLint and ESLint. This article compares them in detail so you can pick the linter that best fits your project’s size, style needs, and workflow.

What a linter does (brief)

A linter analyzes source code for potential errors, stylistic inconsistencies, and patterns that may lead to bugs or maintenance problems. Linters range from strict opinionated tools to highly customizable rule engines.

Origins and philosophy

• JSLint

  • Created in 2002 by Douglas Crockford.
  • Opinionated, minimal configuration: JSLint enforces a single, strict coding style and flags anything it considers risky or stylistically incorrect.
  • Focuses on code safety and best practices as defined by its creator.

• ESLint

  • First released in 2013 by Nicholas C. Zakas.
  • Highly configurable and extensible: ESLint was designed to be pluggable so teams can adopt or build rules that match their preferences.
  • Encourages community-driven rule sets and plugin ecosystem.

Configuration and flexibility

• JSLint

  • Very limited configuration options; many decisions are fixed.
  • Uses a small set of directives (via comments) to toggle a few behaviors.
  • Ideal if you want a strict, uniform style with minimal debate.

• ESLint

  • Supports detailed configuration through .eslintrc files (JSON/YAML/JS).
  • Extensive rule set that can be enabled/disabled and tuned (error/warn/off).
  • Supports plugins for frameworks (React, Vue), TypeScript, custom rules, and shareable configs (e.g., eslint-config-airbnb).
  • Better suited when different projects or teams require different standards.

Rules and extensibility

• JSLint

  • Built-in, fixed rule set; updates come from its maintainer.
  • No plugin system and very limited ability to add new or custom rules.

• ESLint

  • Massive ecosystem of rules and plugins.
  • Ability to write custom rules in JavaScript.
  • Integrates with formatters (Prettier) and other tools; can autofix many issues.

Language and environment support

• JSLint

  • Primarily targets core JavaScript; historically conservative about newer language features.
  • Limited specific support for frameworks, JSX, or TypeScript.

• ESLint

  • Broad support for modern ECMAScript features, JSX, TypeScript (via @typescript-eslint), and many frameworks through plugins.
  • Can parse different syntaxes via configurable parsers (espree, babel-eslint / @babel/eslint-parser, @typescript-eslint/parser).

Error reporting and developer experience

• JSLint

  • Clear, opinionated messages focused on enforcing its style.
  • Less tooling and editor integrations compared to ESLint’s ecosystem.

• ESLint

  • Rich reporting, rule metadata, autofix capability for many rules.
  • Excellent editor integrations (VS Code, Sublime, Atom) and CI tooling.
  • Large community means more guides, stackoverflow answers, and plugin support.

Performance

• JSLint

  • Lightweight because of its smaller, fixed rule set.
  • Fast for small to medium codebases.

• ESLint

  • Performance depends on configuration, plugins, and parser choice.
  • For large projects, ESLint can be tuned (caching, selective linting, worker threads) to perform well.

Use cases and recommendations

• Choose JSLint if:

  • You want a highly opinionated, minimalist linter with very little configuration.
  • You prefer a single authoritative style enforced across a small project or team.
  • You value simplicity over flexibility.

• Choose ESLint if:

  • You need flexibility to match or evolve coding standards across teams or projects.
  • You use modern JavaScript features, JSX, or TypeScript.
  • You want strong editor/CI integration and the ability to autofix issues.
  • You rely on community plugins and shareable configs (Airbnb, Standard, Google).

Comparison table

Migrating from JSLint to ESLint

1. Install ESLint: npm install eslint --save-dev.
2. Initialize config: npx eslint --init and choose options that match your style.
3. Add plugins for environment/features (e.g., eslint-plugin-react, @typescript-eslint).
4. Run ESLint and enable autofix: npx eslint . --fix.
5. Gradually tune rules to match or improve upon JSLint behavior.

Final verdict

If you want strict, low-decision enforcement out of the box, JSLint is a straightforward option. For most modern projects—especially those using JSX, TypeScript, or needing team-specific rules—ESLint is the practical choice because of its configurability, extensibility, and ecosystem.