Rules

jetlint ships 182 rules organized into 7 categories. Five rules form the recommended preset and fire at error severity by default; every other rule is off until opted in via .jetlintrc.json.

Compatibility. 6193 / 6193 typescript-eslint fixtures pass, plus 4405 / 4405 AST-only fixtures across the 112 biome and oxlint ports, plus 71 / 71 hand-written tests for the 9 ESLint-core rules without upstream fixture data — 100% across the board (10669 cases total). Every rule’s score is reproducible from the jetlint repo.

Origin. Type-aware rules were ported from typescript-eslint; AST-only rules from biome and oxlint (which themselves mirror ESLint core for the JS-only rules). The distinction the rule pages care about is type-aware vs AST-only (does the rule cost a TypeScript program load?) so that’s what each row below shows.

Recommended preset

These five fire by default. They map to the consensus between typescript-eslint’s recommendedTypeChecked and oxc’s correctness category — rules upstream tools agree are bug-finders, not opinionated style.

To turn off any recommended rule, set it to off in your config; to add others, opt in by name. See Config.

All rules, by category

The seven categories follow the rubric in docs/RULE-CATEGORIES.md: the first matching framing wins, with correctness beating performance beating complexity for cross-cutting rules. A ★ marks rules in the recommended preset.

correctness — 105 rules

Code that is wrong: runtime bugs, undefined behavior, type holes. No legitimate reason to write.

suspicious — 31 rules

Code that smells. Usually wrong, occasionally intentional. The author should justify or fix.

security — 6 rules

Patterns enabling injection, eval, prototype pollution, or unsafe deserialization.

performance — 16 rules

Known-slow patterns with a faster equivalent. No correctness impact.

complexity — 17 rules

Needless complication with a simpler equivalent. No correctness or perf impact.

style — 7 rules

Formatting, naming, ordering. Pure preference; team-configurable.

nursery — 0 rules

New or iterating rules. May change shape or move to another group. Not included in the recommended preset. Empty today.

Reproducing the compatibility scores

Every rule has a vendored fixture (or inline test cases) and a Go harness. From the jetlint repo:

# typescript-eslint ports (type-aware rules)
go test -count=1 -run TypescriptEslintCompatibility -v \
  ./internal/rules/<rule-package>/

# biome + ESLint-core ports (AST-only rules)
go test -count=1 -run EslintCompatibility -v \
  ./internal/rules/<rule-package>/

The aggregate validates all 182 rules against 10669 cases in one go. See docs/OXLINT-COMPAT-OVERVIEW.md for the AST-only fixture format and how to regenerate from a fresh oxc/biome checkout.