typescript-eslint/typescript-eslint

The primary user surface is ESLint configuration and diagnostics, supported by reusable parser and rule-author APIs. Presets distinguish correctness, strictness, style, and type-information requirements. The browser playground adds editable configurations, diagnostic markers, structural inspection, and shareable examples. The following catalog groups features found in inspected files rather than claiming exhaustive coverage of every rule.

• Users can select recommended, strict, and stylistic presets, their type-checked and type-checked-only variants, all, base, eslintRecommended, or disableTypeChecked.
  packages/typescript-eslint/src/index.ts#L71-117packages/typescript-eslint/src/index.ts#L119-170
• The deprecated config() helper flattens nested arrays and expands object-based extends; it rejects string extensions, nested extends, and basePath inside extensions.
  packages/typescript-eslint/src/config-helper.ts#L91-119packages/typescript-eslint/src/config-helper.ts#L148-184
• The parser exposes parse and parseForESLint alongside createProgram, clearCaches, and helpers for removing project-related parser options.
  packages/parser/src/index.ts#L21-29packages/parser/src/parser.ts#L92-102
• Typed linting accepts project-service configuration, supplied Programs, or legacy project resolution; projectService and project together normally produce a configuration error.
  packages/typescript-estree/src/parseSettings/createParseSettings.ts#L148-161packages/typescript-estree/src/parseSettings/createParseSettings.ts#L184-234
• no-floating-promises detects unhandled Promise-like expressions, supports safe-call/type allowances and thenable/IIFE/void options, and offers await or void suggestions under applicable report branches.
  packages/eslint-plugin/src/rules/no-floating-promises.ts#L28-46packages/eslint-plugin/src/rules/no-floating-promises.ts#L118-154packages/eslint-plugin/src/rules/no-floating-promises.ts#L157-223
• The recommended-type-checked preset enables promise, unsafe-value, assertion, unused-code, and other correctness rules while disabling corresponding core rules where replacements are configured.
  packages/eslint-plugin/src/configs/flat/recommended-type-checked.ts#L25-75
• Rule authors receive RuleCreator with default-option merging and documentation URLs, plus a RuleTester that normalizes filenames and runs rules through a flat-config Linter.
  packages/utils/src/eslint-utils/RuleCreator.ts#L61-95packages/utils/src/eslint-utils/RuleCreator.ts#L114-128packages/rule-tester/src/RuleTester.ts#L203-231packages/rule-tester/src/RuleTester.ts#L292-310
• The playground exposes code, ESLint, and TypeScript configuration editing, error displays, ESTree/scope/TypeScript/type views, ESQuery filtering, and a Ctrl/Cmd-S lint-fix action.
  packages/website/src/components/Playground.tsx#L70-83packages/website/src/components/Playground.tsx#L167-225packages/website/src/components/editor/LoadedEditor.tsx#L230-251