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Merged
sindresorhus merged 5 commits into from
Aug 10, 2026
+718 −41
Merged

custom-error-definition: Support TypeScript parameter properties #3619

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433b55a
`custom-error-definition`: Support TypeScript parameter properties
sindresorhus Aug 10, 2026
55e8be1
`custom-error-definition`: Preserve comments in autofixes
sindresorhus Aug 10, 2026
89a7f90
`custom-error-definition`: Guard unsafe autofixes
sindresorhus Aug 10, 2026
9eafcc9
`custom-error-definition`: Fix computed exports and preserve comments
sindresorhus Aug 10, 2026
99617d7
`custom-error-definition`: Simplify computed exports
sindresorhus Aug 10, 2026
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161 changes: 120 additions & 41 deletions rules/custom-error-definition.js
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Original file line number Diff line number Diff line change
@@ -1,8 +1,10 @@
import {getPropertyName} from '@eslint-community/eslint-utils';
import {getPropertyName, isCommentToken} from '@eslint-community/eslint-utils';
import {
upperFirst,
getParenthesizedText,
hasCommentInRange,
isNodeMatchesNameOrPath,
isParenthesized,
unwrapTypeScriptExpression,
} from './utils/index.js';
import {
Expand Down Expand Up @@ -94,7 +96,7 @@ const isPropertyDefinition = (node, name) =>
&& node.key.name === name;

const isValidNameProperty = (nameProperty, className) =>
getStaticStringValue(nameProperty?.value) === className;
getStaticStringValue(unwrapTypeScriptExpression(nameProperty?.value)) === className;

const isMessageAccessor = (node, kind) =>
node.type === 'MethodDefinition'
Expand All @@ -106,9 +108,13 @@ const isMessageAccessor = (node, kind) =>

const isMissingOrUndefined = node =>
!node
|| isUndefined(node);
|| isUndefined(unwrapTypeScriptExpression(node));

const getParameterIdentifier = parameter => {
if (parameter?.type === 'TSParameterProperty') {
return getParameterIdentifier(parameter.parameter);
}

if (parameter?.type === 'Identifier') {
return parameter;
}
Expand All @@ -122,10 +128,13 @@ const getParameterIdentifier = parameter => {
};

const isOptionsIdentifier = node =>
getParameterIdentifier(node)?.name === 'options';
getParameterIdentifier(unwrapTypeScriptExpression(node))?.name === 'options';

const isSameText = (left, right, sourceCode) =>
sourceCode.getText(left) === sourceCode.getText(right);
const hasCommentImmediatelyAfter = (sourceCode, node) =>
isCommentToken(sourceCode.getTokenAfter(node, {includeComments: true}));

const isSameUnwrappedText = (left, right, sourceCode) =>
sourceCode.getText(unwrapTypeScriptExpression(left)) === sourceCode.getText(unwrapTypeScriptExpression(right));

const hasThisOrSuper = (node, visitorKeys) => {
if (node.type === 'ThisExpression' || node.type === 'Super') {
Expand Down Expand Up @@ -167,7 +176,12 @@ const getOptionsParameterText = firstParameter => {
return parameterIdentifier.optional ? 'options?: ErrorOptions' : 'options: ErrorOptions';
};

const fixSuperOptionsArgument = (sourceCode, superCallExpression, messageArgumentText) => fixer => {
const fixSuperOptionsArgument = (context, superCallExpression, messageArgumentText) => fixer => {
const {sourceCode} = context;
if (sourceCode.getCommentsInside(superCallExpression).length > 0) {
return;
}

const superArguments = superCallExpression.arguments;

if (superArguments.length === 0) {
Expand All @@ -176,6 +190,10 @@ const fixSuperOptionsArgument = (sourceCode, superCallExpression, messageArgumen
}

if (superArguments.length === 1) {
if (isParenthesized(superArguments[0], context)) {
return;
}

if (
messageArgumentText !== 'undefined'
&& isMissingOrUndefined(superArguments[0])
Expand All @@ -189,18 +207,26 @@ const fixSuperOptionsArgument = (sourceCode, superCallExpression, messageArgumen

const fixMissingOptionsParameter = (context, constructor, superCallExpression, messageArgumentText) => function * (fixer) {
const {sourceCode} = context;
const superOptionsFix = fixSuperOptionsArgument(sourceCode, superCallExpression, messageArgumentText)(fixer);
const firstParameter = constructor.value.params[0];
if (hasCommentImmediatelyAfter(sourceCode, firstParameter)) {
return;
}

const superOptionsFix = fixSuperOptionsArgument(context, superCallExpression, messageArgumentText)(fixer);
if (!superOptionsFix) {
return;
}

const firstParameter = constructor.value.params[0];
yield fixer.insertTextAfter(firstParameter, `, ${getOptionsParameterText(firstParameter)}`);
yield superOptionsFix;
};

const fixSuperMessageArgument = (sourceCode, superCallExpression, messageArgumentText) => fixer => {
const fixSuperMessageArgument = (context, superCallExpression, messageArgumentText) => fixer => {
const {sourceCode} = context;
if (sourceCode.getCommentsInside(superCallExpression).length > 0) {
return;
}

const superArguments = superCallExpression.arguments;

if (superArguments.length === 0) {
Expand All @@ -209,26 +235,33 @@ const fixSuperMessageArgument = (sourceCode, superCallExpression, messageArgumen
}

if (isMissingOrUndefined(superArguments[0])) {
if (isParenthesized(superArguments[0], context)) {
return;
}

return fixer.replaceText(
superArguments[0],
superArguments.length === 1 ? `${messageArgumentText}, options` : messageArgumentText,
);
}
};

const isSameIdentifier = (node, identifier) =>
node?.type === 'Identifier'
&& node.name === identifier.name;
const isSameIdentifier = (node, identifier) => {
node = unwrapTypeScriptExpression(node);
return node?.type === 'Identifier'
&& node.name === identifier.name;
};

// Whether `super()` already forwards the error options inline, e.g. `super('Fixed message', {cause})`.
const hasInlineErrorOptions = (superCallExpression, shouldPassMessageToSuper) => {
if (shouldPassMessageToSuper) {
return false;
}

const [messageArgument, optionsArgument] = superCallExpression.arguments;
const [messageArgument, rawOptionsArgument] = superCallExpression.arguments;
const optionsArgument = unwrapTypeScriptExpression(rawOptionsArgument);
return superCallExpression.arguments.length === 2
&& getStaticStringValue(messageArgument) !== undefined
&& getStaticStringValue(unwrapTypeScriptExpression(messageArgument)) !== undefined
&& optionsArgument.type === 'ObjectExpression'
&& optionsArgument.properties.length === 1
&& getPropertyName(optionsArgument.properties[0]) === 'cause';
Expand Down Expand Up @@ -256,7 +289,7 @@ const getErrorOptionsProblem = (context, constructor, superExpression, hasMessag
};

if (!isSameIdentifier(superCallExpression.arguments[0], firstParameterIdentifier)) {
problem.fix = fixSuperOptionsArgument(context.sourceCode, superCallExpression, 'undefined');
problem.fix = fixSuperOptionsArgument(context, superCallExpression, 'undefined');
}

return problem;
Expand Down Expand Up @@ -296,15 +329,15 @@ const getErrorOptionsProblem = (context, constructor, superExpression, hasMessag
return {
node: superCallExpression,
messageId: MESSAGE_ID_PASS_MESSAGE_TO_SUPER,
fix: fixSuperMessageArgument(context.sourceCode, superCallExpression, messageArgumentText),
fix: fixSuperMessageArgument(context, superCallExpression, messageArgumentText),
};
}

if (!isOptionsIdentifier(superCallExpression.arguments[1])) {
return {
node: superCallExpression,
messageId: MESSAGE_ID_PASS_OPTIONS_TO_SUPER,
fix: fixSuperOptionsArgument(context.sourceCode, superCallExpression, messageArgumentText),
fix: fixSuperOptionsArgument(context, superCallExpression, messageArgumentText),
};
}
};
Expand All @@ -321,7 +354,7 @@ function getInvalidErrorNameProblem(constructorBodyNode, constructorBody, errorD
return;
}

if (getStaticStringValue(nameExpression.expression.right) !== name) {
if (getStaticStringValue(unwrapTypeScriptExpression(nameExpression.expression.right)) !== name) {
return createInvalidNameError(nameExpression.expression.right ?? constructorBodyNode, name);
}
}
Expand All @@ -338,8 +371,8 @@ function * getConstructorBodyProblems(context, constructor, errorDefinition) {
const constructorBody = constructorBodyNode.body;
const {hasMessageGetter, hasMessageSetter, checkOptions} = errorDefinition;

const superExpression = constructorBody.find(bodyNode => isSuperExpression(bodyNode));
const superExpressionIndex = constructorBody.findIndex(bodyNode => isSuperExpression(bodyNode));
const superExpression = constructorBody[superExpressionIndex];
const messageExpressionIndex = constructorBody.findIndex(bodyNode => isAssignmentExpression(bodyNode, 'message'));
const hasMessageAccessor = hasMessageGetter || hasMessageSetter;
let hasConstructorBodyProblem = false;
Expand Down Expand Up @@ -374,48 +407,76 @@ function * getConstructorBodyProblems(context, constructor, errorDefinition) {
node: superExpression,
message: 'Pass the error message to `super()` instead of setting `this.message`.',
* fix(fixer) {
if (messageExpressionIndex < superExpressionIndex) {
return;
}

const rhs = expression.expression.right;
const [firstParameter, secondParameter] = constructor.value.params;
const firstParameterIdentifier = getParameterIdentifier(firstParameter);
const shouldAddOptionsParameter = constructor.value.params.length === 1
&& firstParameterIdentifier
&& !isOptionsIdentifier(firstParameter);
const start = messageExpressionIndex === 0
? sourceCode.getRange(constructorBodyNode)[0]
: sourceCode.getRange(constructorBody[messageExpressionIndex - 1])[1];
const [, end] = sourceCode.getRange(expression);

if (
shouldAddOptionsParameter
&& hasCommentImmediatelyAfter(sourceCode, firstParameter)
) {
return;
}

if (hasCommentInRange(context, [start, end])) {
return;
}

if (hasCommentImmediatelyAfter(sourceCode, expression)) {
return;
}

const superCallExpression = superExpression.expression;
if (sourceCode.getCommentsInside(superCallExpression).length > 0) {
return;
}

const shouldAddOptionsArgument = shouldAddOptionsParameter || isOptionsIdentifier(secondParameter);

if (superExpression.expression.arguments.length === 0) {
if (superCallExpression.arguments.length === 0) {
if (
messageExpressionIndex !== superExpressionIndex + 1
|| hasThisOrSuper(rhs, sourceCode.visitorKeys)
) {
return;
}

const [start] = sourceCode.getRange(superExpression);
// This part crashes on ESLint 10, but it's still not correct.
// There can be spaces, comments after `super`
yield fixer.insertTextAfterRange(
[start, start + 6],
// Use the parenthesis token to preserve spacing between `super` and `(`.
const openingParenthesis = sourceCode.getTokenAfter(superCallExpression.callee, token => token.value === '(');
yield fixer.insertTextAfter(
openingParenthesis,
shouldAddOptionsArgument
? `${getParenthesizedText(rhs, context)}, options`
: getParenthesizedText(rhs, context),
);
} else if (!isSameText(superExpression.expression.arguments[0], rhs, sourceCode)) {
} else if (!isSameUnwrappedText(superCallExpression.arguments[0], rhs, sourceCode)) {
return;
} else if (
shouldAddOptionsArgument
&& superExpression.expression.arguments.length === 1
&& superCallExpression.arguments.length === 1
) {
yield fixer.insertTextAfter(superExpression.expression.arguments[0], ', options');
if (isParenthesized(superCallExpression.arguments[0], context)) {
return;
}

yield fixer.insertTextAfter(superCallExpression.arguments[0], ', options');
}

if (shouldAddOptionsParameter) {
yield fixer.insertTextAfter(firstParameter, `, ${getOptionsParameterText(firstParameter)}`);
}

const start = messageExpressionIndex === 0
? sourceCode.getRange(constructorBodyNode)[0]
: sourceCode.getRange(constructorBody[messageExpressionIndex - 1])[1];
const [, end] = sourceCode.getRange(expression);
yield fixer.removeRange([start, end]);
},
};
Expand Down Expand Up @@ -458,7 +519,8 @@ function * customErrorDefinition(context, node) {

const {body} = node.body;
const {sourceCode} = context;
const constructor = body.find(x => x.kind === 'constructor');
const constructor = body.find(classNode => classNode.kind === 'constructor' && classNode.value.body)
?? body.find(classNode => classNode.kind === 'constructor');
const nameProperty = body.find(classNode => isPropertyDefinition(classNode, 'name'));

if (!constructor) {
Expand All @@ -471,6 +533,15 @@ function * customErrorDefinition(context, node) {
...createInvalidNameError(nameProperty?.value ?? node, name),
fix(fixer) {
if (nameProperty?.value) {
const value = unwrapTypeScriptExpression(nameProperty.value);
if (getStaticStringValue(value) !== undefined) {
return fixer.replaceText(value, `'${name}'`);
}

if (sourceCode.getCommentsInside(nameProperty.value).length > 0) {
return;
}

return fixer.replaceText(nameProperty.value, `'${name}'`);
}

Expand Down Expand Up @@ -500,7 +571,7 @@ function * customErrorDefinition(context, node) {
});
}

const customErrorExport = (context, node) => {
const customErrorExport = node => {
const maybeError = node.right;

if (maybeError.type !== 'ClassExpression') {
Expand All @@ -517,16 +588,24 @@ const customErrorExport = (context, node) => {

// Assume rule has already fixed the error name
const errorName = maybeError.id.name;
const exportsName = node.left.property.name;

if (exportsName === errorName) {
const isComputed = node.left.computed;
const exportProperty = node.left.property;
const exportPropertyValue = unwrapTypeScriptExpression(exportProperty);
const exportsName = isComputed
? getStaticStringValue(exportPropertyValue)
: exportProperty.name;

if (exportsName === undefined || exportsName === errorName) {
return;
}

const propertyToReplace = isComputed ? exportPropertyValue : exportProperty;
const replacementText = isComputed ? `'${errorName}'` : errorName;

return {
node: node.left.property,
node: exportProperty,
messageId: MESSAGE_ID_INVALID_EXPORT,
fix: fixer => fixer.replaceText(node.left.property, errorName),
fix: fixer => fixer.replaceText(propertyToReplace, replacementText),
};
};

Expand All @@ -544,7 +623,7 @@ const create = context => {
&& node.left.object.type === 'Identifier'
&& node.left.object.name === 'exports'
) {
return customErrorExport(context, node);
return customErrorExport(node);
}
});
};
Expand Down
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