All Rules

Danger

Flint is still very early stage and experimental. Not all features have been implemented.

Tip

Rules are grouped into plugins that you can opt into. See Rules for an overview of how rules are sorted into plugins.

These rules will not be implemented as a part of Flint. They are all too opinionated and/or too niche to be kept in the Flint project. They’re free to be implemented as a community third-party Flint plugin.

Total count: 474

Flint Rule	Plugin	Notes
abbreviations	TypeScript
aboutSchemaDescriptions	Flint
aboutSchemas	Flint
aboutSuggestions	Flint
aboutTypes	Flint
accessorPairs	TypeScript
adjacentInlineElements	JSX	Overly opinionated.
argumentsArrayMethods	TypeScript
argumentsProperties	TypeScript
arrayDestructuringSparsity	TypeScript
arrayElementsSorting	JSON
arrayFlatDepthMagicNumbers	TypeScript
arrayJoinSeparators	TypeScript
arrayMethodThisArguments	TypeScript
arrayReducers	TypeScript
arraySortCompareArgument	TypeScript
arrowBodyBraces	TypeScript
arrowCallbacks	TypeScript
asciiCharacters	Node.js
assignmentOperationRefactors	TypeScript
asyncAwaitStatements	TypeScript
asyncStores	Svelte	Svelte 4-exclusive rule.
atomicUpdates	TypeScript
attributeEqualSignSpaces	Svelte	Formatting rule.
attributeEqualSignSpaces	Vue	Formatting rule.
attributeLinebreaks	Vue	Formatting rule.
attributeNameValidity	Vue	Generally handled by parsers.
attributeOrdering	Svelte	Superseded by the sorting plugin's jsxProps rules.
attributesLineLimits	Svelte	Formatting rule.
attributesPerLine	Vue	Formatting rule.
awaitInsidePromiseMethods	TypeScript	Superseded by awaitThenable.
awaitMemberAccesses	TypeScript
barrelFiles	TypeScript
bigintLiterals	JSON	Generally handled by parsers.
binaryExpressions	JSON	Generally handled by parsers.
binaryNumericLiterals	JSON	Generally handled by parsers.
bitwiseOperatorLogic	TypeScript
bitwiseOperators	TypeScript
blankLineMultiples	Markdown	Formatting rule.
blockquoteSpaces	Markdown	Formatting rule.
blockStatements	TypeScript	Superseded by prettier-plugin-curly
booleanCoercionMatchers	Vitest	Overly opinionated.
booleanLiteralParameterComments	TypeScript
builtinPrototypeMethodAccesses	TypeScript
callbackErrorHandling	Node.js
callbackErrorLiterals	Node.js
callbackReturns	Node.js
capitalizedConstructors	TypeScript
childrenCurlyBraces	JSX	Formatting rule.
classComponentDefinitions	React	create-react-class is long-outdated.
closingBracketNewlines	Vue	Formatting rule.
closingBracketSpacing	JSX	Formatting rule.
closingBracketSpacing	Vue	Formatting rule.
closingTagSpacing	JSX	Formatting rule.
codeblockBlankLines	Markdown	Formatting rule.
codeBlockStyles	Markdown	Formatting rule.
codeFenceStyles	Markdown	Formatting rule.
commandOutputs	Markdown	Overly opinionated.
commentCapitalization	TypeScript
commentDirectives	Svelte	Generally handled by parsers.
comments	JSON	Generally handled by parsers.
commentWarnings	TypeScript
comparisonSequences	TypeScript	Handled by TypeScript / otherwise is stylistic.
compiles	Astro	Handled by the Astro compiler.
componentNameCases	JSX	Overly opinionated and brittle.
componentOptimizations	React	Overly opinionated.
componentPropertySorting	React	Handled by ts sorting preset.
componentsPerFile	React	Overly opinionated.
conditionalAssignments	TypeScript	Superseded by unnecessaryConditions.
conditionNegations	TypeScript
conditionOrdering	TypeScript
consistentReturns	TypeScript
constantBinaryExpressions	TypeScript	Superseded by unnecessaryConditions.
constantConditions	TypeScript	Superseded by unnecessaryConditions.
constEnums	TypeScript
constVariables	Svelte	Superseded by js plugin's constVariables rule.
continues	TypeScript
crossComponentPropTypes	React	Overly opinionated and for the no-longer-recommended propTypes pattern
crossComponentPropTypes	React	Superseded by deprecated.
curlyNewlines	JSX	Formatting rule.
curlySpacing	JSX	Formatting rule.
defaultCases	TypeScript
defaultImportRenames	TypeScript
defaultParameterReassignments	TypeScript
defaultPropObjectValues	JSX	Overly opinionated.
defaultPropsSoring	React	Handled by ts sorting preset.
deprecatedAPIs	Node.js	Superseded by deprecated.
deprecatedAstroCanonicalURL	Astro	Superseded by deprecated.
deprecatedAstroFetchContent	Astro	Superseded by deprecated.
deprecatedAstroResolve	Astro	Superseded by deprecated.
deprecatedBindSyncs	Vue	Superseded by deprecated.
deprecatedContextMethods	Flint
deprecatedDollarListeners	Vue	Superseded by deprecated.
deprecatedDollarScopedSlots	Vue	Superseded by deprecated.
deprecatedEvents	Vue	Superseded by deprecated.
deprecatedGetEntryBySlug	Astro	Superseded by deprecated.
deprecatedHtmlElementIs	Vue	Superseded by deprecated.
deprecatedInlineTemplates	Vue	Superseded by deprecated.
deprecatedMessagePlaceholders	Flint
deprecatedMessageStrings	Flint
deprecatedModelDefinitions	Vue	Superseded by deprecated.
deprecatedReplacedBy	Flint
deprecatedReportAPIs	Flint
deprecatedRouterLinkTagProps	Vue	Superseded by deprecated.
deprecatedRuleFunctions	Flint
deprecatedSchemaDefaults	Flint
deprecatedScopeAttributes	Vue	Superseded by deprecated.
deprecatedSetDeletes	Vue	Superseded by deprecated.
deprecatedSlotAttributes	Vue	Superseded by deprecated.
deprecatedSlotScopeAttributes	Vue	Superseded by deprecated.
deprecatedTextReplacements	Flint
deprecatedVIs	Vue	Superseded by deprecated.
deprecatedVOnNativeModifiers	Vue	Superseded by deprecated.
deprecatedVOnNumberModifiers	Vue	Superseded by deprecated.
deprecatedVueConfigKeyCodes	Vue	Superseded by deprecated.
derivedCallbackNamingConsistency	Svelte	Svelte 4-exclusive rule.
destructuredStoreProps	Svelte	Svelte 4-exclusive rule.
destructuring	TypeScript
directiveDisableSelectors	TypeScript	Core requires explicit disables
directiveDuplicateDisables	TypeScript	Core detects duplicate disables
directiveMisleadingEnables	TypeScript	Core requires explicit enables
directiveRestrictedDisables	TypeScript
directiveSelectors	TypeScript	Handled by Flint core
directiveUnknownRules	TypeScript	Handled by Flint core
directiveUnlimitedDisables	TypeScript	Core requires explicit disables
directiveUnused	TypeScript	Handled by Flint core
directiveUnusedDisables	TypeScript	Core detects unused disables
directiveUnusedEnables	TypeScript	Core detects unused enables
duplicateOnDirectives	Svelte	Svelte 4-exclusive rule.
duplicateProps	SolidJS	Superseded by jsx plugin's duplicateProps rule.
duplicateSpreads	JSX
dynamicSlotNames	Svelte	Deprecated. Now handled by the Svelte compiler.
emphasisMarkerSpacing	Markdown
emphasisSpaces	Markdown	Formatting rule.
emphasisStyles	Markdown	Formatting rule.
emptyTestTodos	Vitest	Overly opinionated.
endingTernaryIfElses	TypeScript
equalityMatchers	Vitest	Overly opinionated.
equalsSpacing	JSX	Formatting rule.
eventDispatcherTypes	Svelte	Svelte 4-exclusive rule.
exportDefault	TypeScript
exportGroups	TypeScript
exportLast	TypeScript
exportsStyle	Node.js	CJS-specific.
expressionsPerLine	JSX	Formatting rule.
externalHttpImports	TypeScript
extraneousRequires	Node.js	Superseded by Knip
extraReactiveCurlies	Svelte	Svelte 4-exclusive rule.
filenameCasing	TypeScript
filenameExtensions	JSX	Generally handled by parsers.
fileTrailingNewlines	Markdown	Formatting rule.
findDOMNodeCalls	React	Superseded by deprecated.
firstAttributeLinebreaks	Svelte	Formatting rule.
fixerReturns	Flint
floatingDecimals	JSON	Generally handled by parsers.
forwardRefArguments	React	`React.forwardRef` is no longer necessary as of React 19.
functionBinds	JSX	Overly opinionated.
functionNames	TypeScript
functionReactivity	Svelte	Svelte 4-exclusive rule.
functionReturnTypes	TypeScript
globalBuffer	Node.js
globalConsole	Node.js
globalProcess	Node.js
globalTextDecoder	Node.js
globalTextEncoder	Node.js
globalURL	Node.js
globalURLSearchParams	Node.js
gotosLackingBase	Svelte	Deprecated. Superseded by unresolvedNavigations.
handlerNames	JSX	Overly opinionated.
hardTabs	Markdown	Formatting rule.
headingBlankLines	Markdown	Formatting rule.
headingClosingSpaceMultiples	Markdown	Formatting rule.
headingClosingSpaceMultiples	Markdown	Formatting rule.
headingClosingSpaces	Markdown	Formatting rule.
headingIndents	Markdown	Formatting rule.
headingMissingSpaces	Markdown	Formatting rule.
headingPresence	Markdown	Overly opinionated.
headingSpaces	Markdown	I intend to write a Prettier plugin.
headingStyles	Markdown	Formatting rule.
hexadecimalNumericLiterals	JSON	Generally handled by parsers.
hexEscapes	TypeScript
hookContents	Vitest	Overly opinionated.
hooks	Vitest	Overly opinionated.
hrStyles	Markdown	Formatting rule.
html	Markdown
htmlClosingBracketNewLine	Svelte	Formatting rule.
htmlClosingBracketSpacings	Svelte	Formatting rule.
htmlQuotes	Svelte	Formatting rule.
htmlQuotes	Vue	Formatting rule.
htmlTagsSelfClosing	Vue	Formatting rule.
identifierEscapeSequences	JSON	Generally handled by parsers.
identifierMatches	TypeScript
identifierNumbers	JSON	Generally handled by parsers.
ignoredUnsubscribes	Svelte	Svelte 4-exclusive rule.
iifeReadability	TypeScript
imageAltRedundancy	JSX
immutableReactiveStatements	Svelte	Svelte 4-exclusive rule.
implicitCoercions	TypeScript
importAbsolutePaths	TypeScript
importAssertions	TypeScript	Generally handled by parsers.
importDefaults	TypeScript	Handled by TypeScript
importDuplicates	TypeScript
importFirst	TypeScript
importMaximumDependencies	TypeScript
importNameMatches	TypeScript
importNamespaceProperties	TypeScript	Handled by TypeScript
importNamespaces	TypeScript
importsSorting	TypeScript
indentation	Svelte	Formatting rule.
indents	JSX	Formatting rule.
indents	Vue	Formatting rule.
infinity	JSON	Generally handled by parsers.
inlineComments	TypeScript
innerDeclarations	Svelte
innerDeclarations	TypeScript
isMounted	React	`isMounted` is no longer present in modern React.
iterableKeys	JSX
iteratorMethodFunctionReferences	TypeScript
jsdocAlignment	TypeScript	I intend to write a Prettier plugin.
jsdocBlankBlockDescriptions	TypeScript
jsdocConvertToJSDocComments	TypeScript
jsdocDefaults	TypeScript
jsdocDefinedTypes	TypeScript
jsdocDescriptionCompleteSentences	TypeScript
jsdocDescriptions	TypeScript
jsdocExamples	TypeScript
jsdocFileOverviews	TypeScript
jsdocImportsAsDependencies	TypeScript
jsdocIndentation	TypeScript	I intend to write a Prettier plugin.
jsdocLineAlignment	TypeScript	I intend to write a Prettier plugin.
jsdocMatchDescriptions	TypeScript
jsdocMatchNames	TypeScript
jsdocMissingSyntax	TypeScript
jsdocParameterDescriptions	TypeScript
jsdocParameters	TypeScript
jsdocParameterTypes	TypeScript
jsdocProperties	TypeScript
jsdocPropertyDescriptions	TypeScript
jsdocPropertyTypes	TypeScript
jsdocRequired	TypeScript
jsdocReturnDescriptions	TypeScript
jsdocReturns	TypeScript
jsdocReturnTypes	TypeScript
jsdocTagLines	TypeScript
jsdocTemplates	TypeScript
jsdocTextEscaping	TypeScript
jsdocThrows	TypeScript
jsonImportAttributes	TypeScript
keyCasing	JSON
keyContents	JSON
labels	TypeScript
labelVariableNames	TypeScript
lifecycleMethodArrowFunctions	JSX	Overly opinionated.
liIndents	Markdown	Formatting rule.
lineLengths	Markdown	Formatting rule.
linesPerBlockLimits	Svelte	Overly opinionated.
linkBlankLines	Markdown	Formatting rule.
linkImageStyles	Markdown	Formatting rule.
linkSpaces	Markdown
listMarkerSpaces	Markdown	Formatting rule.
listStyles	Markdown	Formatting rule.
literalReactivity	Svelte	Svelte 4-exclusive rule.
literals	JSX	Overly opinionated.
loopConditionConstants	TypeScript
magicNumbers	TypeScript
mappedObjectSpreads	Performance
mappingKeyCasing	YAML
mathRangeTernaries	TypeScript
mathTruncationOperators	TypeScript
maximumChildrenDepth	JSX	Overly opinionated.
maximumClassesPerFile	TypeScript
maximumComplexity	TypeScript
maximumComponentsPerFile	Vue	Overly opinionated.
maximumDepth	TypeScript
maximumExpects	Vitest	Overly opinionated.
maximumIdentifierLengths	TypeScript
maximumLinesPerFile	TypeScript
maximumLinesPerFunction	TypeScript
maximumNestedCallbacks	TypeScript
maximumNestedDescribes	Vitest	Overly opinionated.
maximumParameters	TypeScript
maximumPropsPerLine	JSX	Formatting rule.
maximumStatements	TypeScript
memberAccessibility	TypeScript
memberOrderings	TypeScript	Superseded by sorting plugin rules.
messageIdMismatches	Flint
misleadingSemicolons	JSX
misleadingShorthandAssignments	TypeScript
misleadingThenProperties	TypeScript
missingImports	Node.js
missingRequires	Node.js
mixedRequires	Node.js	Superseded by ESM and ordering rules.
mocksDirectoryImports	Vitest	Overly opinionated.
moduleBoundaryTypes	TypeScript
moduleFormats	TypeScript
moduleImportStyles	TypeScript
multilineElementContentNewlines	Vue	Formatting rule.
multilineStrings	TypeScript
multipleElseIfSwitches	TypeScript
mustacheInterpolationSpaces	Vue	Formatting rule.
mustacheSpacings	Svelte	Formatting rule.
namespaces	JSX	Generally handled by parsers.
namingConventions	TypeScript
nan	JSON	Generally handled by parsers.
navigationLackingBase	Svelte	Deprecated. Superseded by unresolvedNavigations.
newlines	JSX	Formatting rule.
newRequires	Node.js
nodeGlobals	Node.js
nonFunctionHandlers	Svelte	Svelte 4-exclusive rule.
noScriptUrl	SolidJS	Superseded by jsx plugin's duplicateProps rule.
nulls	TypeScript
numberKeyLiterals	TypeScript
numbers	JSON	Generally handled by parsers.
numberToFixedDigits	TypeScript
numericConstantApproximations	TypeScript
numericLiteralCasing	TypeScript	Formatting rule.
numericSeparators	JSON	Generally handled by parsers.
objectDefaultParameters	TypeScript
objectLiteralComparisons	TypeScript
octalEscapeSequences	JSON	Generally handled by parsers.
octalLiterals	JSON	Generally handled by parsers.
octalNumericLiterals	JSON	Generally handled by parsers.
optionalChainExpressions	TypeScript
optionDefaults	Flint
parameterProperties	TypeScript
parentheses	JSON	Generally handled by parsers.
parsingErrors	Vue	Generally handled by parsers.
pathConcatenations	Node.js
plusOperators	JSON	Generally handled by parsers.
plusPlusOperators	TypeScript
pollingAwaits	Vitest	Superseded by floatingPromises.
prefixedClassLikes	TypeScript
processEnvs	Node.js
processExitThrows	Node.js
promiseAlwaysReturn	TypeScript	Superseded by floatingPromises.
promiseArgumentCounts	TypeScript
promiseAwaitableCallbacks	TypeScript
promiseAwaitableThens	TypeScript
promiseCallbackFunctions	Node.js
promiseCatchableThens	TypeScript
promiseCatchOrReturn	TypeScript	Superseded by floatingPromises.
promiseErrorFirstCallbacks	TypeScript	Superseded by floatingPromises.
promiseExecutorReturns	TypeScript	Superseded by awaitThenable.
promiseExpectChains	Vitest	Superseded by floatingPromises.
promiseFinallyReturns	TypeScript	Largely covered by returnVoidSafety.
promiseNesting	TypeScript
promiseNews	TypeScript
promiseNewStatics	TypeScript
promiseNonSpecMethods	TypeScript	Superseded by floatingPromises.
promiseParameterNames	TypeScript
promisesDNS	Node.js
promisesFS	Node.js
propDefaults	React	Overly opinionated.
properNames	Markdown	Superseded by cspell.
propertyOrdering	Flint
propIndents	JSX	Formatting rule.
propNewlines	JSX	Formatting rule.
propsSorting	JSX	Superseded by jsx sorting preset
propsSpaces	JSX	Formatting rule.
propsSpreads	JSX	Overly opinionated.
propTypesExactness	React	Handles an edge case in the no-longer-recommended propTypes package.
propTypesMutability	React	Overly opinionated.
propTypesSorting	React	Handled by ts sorting preset.
prototypeIterators	TypeScript
proxyApis	SolidJS	Modern environments generally support Proxy.
reactJsxScopes	React	Generally handled by parsers.
readonlyClassProperties	TypeScript
readonlyParameterTypes	TypeScript	Better suited to a functional/immutable-focused plugin.
reflectApplies	TypeScript
regexConciseness	TypeScript	Superseded by other regex cleanliness rules
regexConsecutiveSpaces	TypeScript
regexDivisionStarts	TypeScript
regexLegacyFeatures	TypeScript	Superseded by deprecated.
regexTopLevelDeclarations	TypeScript
regexUnicodeSetsFlag	TypeScript
renderReturns	React	`render` is no longer recommended in modern React.
requireVariables	TypeScript
restrictedDirectives	TypeScript
restrictedExports	TypeScript
restrictedHtmlElements	Svelte	Superseded by js plugin's restrictedSyntax rule.
restrictedJSDocs	TypeScript
restrictedRequires	Node.js
restSpreadProperties	TypeScript
ruleAboutChangers	Flint
scriptUrls	JSX	No longer necessary in modern browsers.
selfClosingTags	SolidJS	Superseded by js plugin's selfClosingTags rule.
setStates	React	Overly opinionated.
shoutyConstants	TypeScript
singleLineElementContentNewlines	Vue	Formatting rule.
slotTypes	Svelte	Svelte 4-exclusive rule.
slowTypes	TypeScript
snapshotHints	Vitest	Overly opinionated.
snapshotInterpolations	Vitest	Overly opinionated.
snapshotSizes	Vitest	Overly opinionated.
spaces	Vue	Formatting rule.
spyOnMocks	Vitest	Overly opinionated.
stateAccessesInSets	JSX	Overly opinionated.
storeCallbackSetParameters	Svelte	Svelte 4-exclusive rule.
storeInitializations	Svelte	Svelte 4-exclusive rule.
storeReactiveAccess	Svelte	Svelte 4-exclusive rule.
strictEqualityMatchers	Vitest	Overly opinionated.
strictEvents	Svelte	Svelte 4-exclusive rule.
strictMode	TypeScript
stringConcatenationTemplates	TypeScript
stringContents	TypeScript
stringRawEscapes	TypeScript
stringReplaceAllRegexSearches	TypeScript
stringStartsEndsWithMethods	TypeScript
stringTemplateCurlies	TypeScript
stringTrimMethods	TypeScript	Superseded by deprecated.
strongStyles	Markdown	Formatting rule.
svelteSystem	Svelte	Generally handled by parsers.
switchCaseBraces	TypeScript
switchExhaustiveness	TypeScript
syncFunctionAwaits	TypeScript	Generally handled by parsers.
syncFunctionInAsyncFunctions	Node.js
synchronousMethods	Node.js
tableBlankLines	Markdown	Formatting rule.
tableColumnStyles	Markdown	Formatting rule.
tablePipeStyles	Markdown	Formatting rule.
tagSpaces	JSX	Formatting rule.
templateIndents	TypeScript
templateLiterals	JSON	Generally handled by parsers.
ternaryNesting	TypeScript
ternaryOperators	TypeScript
testCaseOnlies	Vitest	Handled by Vitest in CI mode.
testCaseTitles	Vitest	Overly opinionated.
testConditionalDefinitions	Vitest	Overly opinionated.
testDisables	Vitest	Handled by Vitest in CI mode.
testNames	Flint
testOutputNulls	Flint
testOutputs	Flint
testPropertyOrders	Flint
testReturnStatements	Vitest	Overly opinionated, and largely handled by TypeScript.
textEncodingCases	TypeScript
thisInStatic	TypeScript
toBeObjectMatchers	Vitest	Overly opinionated.
todoExpirations	TypeScript
todoTestSkips	Vitest	Handled by Vitest in CI mode.
topLevelInteroperability	JSON
topLevelRequires	Node.js	CJS-specific.
toThrowMessages	Vitest	Overly opinionated.
trailingSpaces	Markdown	Formatting rule.
trailingSpaces	Svelte
typeAliases	TypeScript
typeAnnotations	TypeScript
typeChecksTypeErrors	TypeScript
ulIndents	Markdown	Formatting rule.
unassignedImports	TypeScript
undefined	JSON	Generally handled by parsers.
undefinedComponents	SolidJS	Handled by ts plugin's undefinedVariables rule.
undefinedNames	TypeScript
underscoreNames	TypeScript
unicodeCodepointEscapes	JSON	Generally handled by parsers.
unnecessaryConditions	Svelte	Deprecated. No longer needed when using svelte-eslint-parser>=v0.19.0.
unnecessaryLabels	TypeScript
unnecessaryPolyfills	TypeScript	Superseded by the e18e initiative
unnecessaryStringRaws	TypeScript
unnecessaryTokenRanges	Flint
unpublishedRequires	Node.js
unreachableLoops	TypeScript
unsupportedGlobals	Node.js
unsupportedSyntax	Node.js
unusedCatchBindings	TypeScript	Superseded by unusedVariables
unusedObjectProperties	TypeScript
urlRelativity	TypeScript
usesReactPragmas	React	Generally handled by parsers.
validCompilations	Svelte	Provided by language reports.
variableDeclarationInitializations	TypeScript
variableDeclarationSorting	TypeScript
variablesOnTop	TypeScript
verbatimModuleSyntax	TypeScript
vitestGlobalImports	Vitest	For a no-longer-recommended globals style.
wrappedMultilines	JSX	Formatting rule.