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fiskersindresorhus
fisker
and
sindresorhus
authoredJan 24, 2025··
Add no-named-default rule (#2538)
Co-authored-by: Sindre Sorhus <sindresorhus@gmail.com>
·
v58.0.0v57.0.0
1 parent 2985ecc commit ed8da1b

11 files changed

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-43
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‎docs/rules/no-named-default.md

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# Disallow named usage of default import and export
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💼 This rule is enabled in the ✅ `recommended` [config](https://github.com/sindresorhus/eslint-plugin-unicorn#preset-configs-eslintconfigjs).
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🔧 This rule is automatically fixable by the [`--fix` CLI option](https://eslint.org/docs/latest/user-guide/command-line-interface#--fix).
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<!-- end auto-generated rule header -->
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<!-- Do not manually modify this header. Run: `npm run fix:eslint-docs` -->
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Enforces the use of the [`default import`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/import) and [`default export`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/export#using_the_default_export) syntax instead of named syntax.
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## Examples
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```js
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// ❌
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import {default as foo} from 'foo';
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// ✅
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import foo from 'foo';
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```
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```js
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// ❌
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import {default as foo, bar} from 'foo';
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// ✅
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import foo, {bar} from 'foo';
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```
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```js
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// ❌
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export {foo as default};
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// ✅
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export default foo;
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```
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```js
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// ❌
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export {foo as default, bar};
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// ✅
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export default foo;
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export {bar};
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```
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```js
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// ❌
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import foo, {default as anotherFoo} from 'foo';
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function bar(foo) {
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doSomeThing(anotherFoo, foo);
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}
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// ✅
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import foo from 'foo';
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import anotherFoo from 'foo';
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function bar(foo) {
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doSomeThing(anotherFoo, foo);
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}
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// ✅
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import foo from 'foo';
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const anotherFoo = foo;
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function bar(foo) {
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doSomeThing(anotherFoo, foo);
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}
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```

‎readme.md

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@@ -94,6 +94,7 @@ export default [
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| [no-length-as-slice-end](docs/rules/no-length-as-slice-end.md) | Disallow using `.length` as the `end` argument of `{Array,String,TypedArray}#slice()`. | ✅ | 🔧 | |
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| [no-lonely-if](docs/rules/no-lonely-if.md) | Disallow `if` statements as the only statement in `if` blocks without `else`. | ✅ | 🔧 | |
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| [no-magic-array-flat-depth](docs/rules/no-magic-array-flat-depth.md) | Disallow a magic number as the `depth` argument in `Array#flat(…).` | ✅ | | |
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| [no-named-default](docs/rules/no-named-default.md) | Disallow named usage of default import and export. | ✅ | 🔧 | |
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| [no-negated-condition](docs/rules/no-negated-condition.md) | Disallow negated conditions. | ✅ | 🔧 | |
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| [no-negation-in-equality-check](docs/rules/no-negation-in-equality-check.md) | Disallow negated expression in equality check. | ✅ | | 💡 |
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| [no-nested-ternary](docs/rules/no-nested-ternary.md) | Disallow nested ternary expressions. | ✅ | 🔧 | |

‎rules/fix/index.js

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@@ -12,6 +12,7 @@ export {default as replaceReferenceIdentifier} from './replace-reference-identif
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export {default as renameVariable} from './rename-variable.js';
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export {default as replaceNodeOrTokenAndSpacesBefore} from './replace-node-or-token-and-spaces-before.js';
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export {default as removeSpacesAfter} from './remove-spaces-after.js';
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export {default as removeSpecifier} from './remove-specifier.js';
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export {default as fixSpaceAroundKeyword} from './fix-space-around-keywords.js';
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export {default as replaceStringRaw} from './replace-string-raw.js';
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export {default as addParenthesizesToReturnOrThrowExpression} from './add-parenthesizes-to-return-or-throw-expression.js';

‎rules/fix/remove-specifier.js

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import {isCommaToken, isOpeningBraceToken} from '@eslint-community/eslint-utils';
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export default function * removeSpecifier(specifier, fixer, sourceCode, keepDeclaration = false) {
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const declaration = specifier.parent;
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const {specifiers} = declaration;
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if (specifiers.length === 1 && !keepDeclaration) {
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yield fixer.remove(declaration);
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return;
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}
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switch (specifier.type) {
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case 'ImportSpecifier': {
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const isTheOnlyNamedImport = specifiers.every(node => specifier === node || specifier.type !== node.type);
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if (isTheOnlyNamedImport) {
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const fromToken = sourceCode.getTokenAfter(specifier, token => token.type === 'Identifier' && token.value === 'from');
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const hasDefaultImport = specifiers.some(node => node.type === 'ImportDefaultSpecifier');
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const startToken = sourceCode.getTokenBefore(specifier, hasDefaultImport ? isCommaToken : isOpeningBraceToken);
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const tokenBefore = sourceCode.getTokenBefore(startToken);
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yield fixer.replaceTextRange(
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[startToken.range[0], fromToken.range[0]],
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tokenBefore.range[1] === startToken.range[0] ? ' ' : '',
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);
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return;
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}
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// Fallthrough
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}
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case 'ExportSpecifier':
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case 'ImportNamespaceSpecifier':
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case 'ImportDefaultSpecifier': {
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yield fixer.remove(specifier);
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const tokenAfter = sourceCode.getTokenAfter(specifier);
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if (isCommaToken(tokenAfter)) {
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yield fixer.remove(tokenAfter);
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}
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break;
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}
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// No default
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}
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}

‎rules/index.js

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@@ -39,6 +39,7 @@ import noKeywordPrefix from './no-keyword-prefix.js';
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import noLengthAsSliceEnd from './no-length-as-slice-end.js';
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import noLonelyIf from './no-lonely-if.js';
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import noMagicArrayFlatDepth from './no-magic-array-flat-depth.js';
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import noNamedDefault from './no-named-default.js';
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import noNegatedCondition from './no-negated-condition.js';
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import noNegationInEqualityCheck from './no-negation-in-equality-check.js';
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import noNestedTernary from './no-nested-ternary.js';
@@ -166,6 +167,7 @@ const rules = {
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'no-length-as-slice-end': createRule(noLengthAsSliceEnd, 'no-length-as-slice-end'),
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'no-lonely-if': createRule(noLonelyIf, 'no-lonely-if'),
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'no-magic-array-flat-depth': createRule(noMagicArrayFlatDepth, 'no-magic-array-flat-depth'),
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'no-named-default': createRule(noNamedDefault, 'no-named-default'),
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'no-negated-condition': createRule(noNegatedCondition, 'no-negated-condition'),
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'no-negation-in-equality-check': createRule(noNegationInEqualityCheck, 'no-negation-in-equality-check'),
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'no-nested-ternary': createRule(noNestedTernary, 'no-nested-ternary'),

‎rules/no-named-default.js

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import {removeSpecifier} from './fix/index.js';
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import assertToken from './utils/assert-token.js';
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const MESSAGE_ID = 'no-named-default';
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const messages = {
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[MESSAGE_ID]: 'Prefer using the default {{type}} over named {{type}}.',
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};
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const isValueImport = node => !node.importKind || node.importKind === 'value';
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const isValueExport = node => !node.exportKind || node.exportKind === 'value';
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const fixImportSpecifier = (importSpecifier, {sourceCode}) => function * (fixer) {
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const declaration = importSpecifier.parent;
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yield * removeSpecifier(importSpecifier, fixer, sourceCode, /* keepDeclaration */ true);
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const nameText = sourceCode.getText(importSpecifier.local);
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const hasDefaultImport = declaration.specifiers.some(({type}) => type === 'ImportDefaultSpecifier');
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// Insert a new `ImportDeclaration`
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if (hasDefaultImport) {
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const fromToken = sourceCode.getTokenBefore(declaration.source, token => token.type === 'Identifier' && token.value === 'from');
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const text = `import ${nameText} ${sourceCode.text.slice(fromToken.range[0], declaration.range[1])}`;
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yield fixer.insertTextBefore(declaration, `${text}\n`);
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return;
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}
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const importToken = sourceCode.getFirstToken(declaration);
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assertToken(importToken, {
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expected: {type: 'Keyword', value: 'import'},
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ruleId: 'no-named-default',
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});
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const shouldAddComma = declaration.specifiers.some(specifier => specifier !== importSpecifier && specifier.type === importSpecifier.type);
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yield fixer.insertTextAfter(importToken, ` ${nameText}${shouldAddComma ? ',' : ''}`);
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};
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const fixExportSpecifier = (exportSpecifier, {sourceCode}) => function * (fixer) {
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const declaration = exportSpecifier.parent;
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yield * removeSpecifier(exportSpecifier, fixer, sourceCode);
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const text = `export default ${sourceCode.getText(exportSpecifier.local)};`;
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yield fixer.insertTextBefore(declaration, `${text}\n`);
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};
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/** @param {import('eslint').Rule.RuleContext} context */
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const create = context => ({
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ImportSpecifier(specifier) {
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if (!(
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isValueImport(specifier)
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&& specifier.imported.name === 'default'
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&& isValueImport(specifier.parent)
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)) {
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return;
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}
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return {
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node: specifier,
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messageId: MESSAGE_ID,
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data: {type: 'import'},
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fix: fixImportSpecifier(specifier, context),
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};
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},
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ExportSpecifier(specifier) {
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if (!(
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isValueExport(specifier)
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&& specifier.exported.name === 'default'
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&& isValueExport(specifier.parent)
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&& !specifier.parent.source
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)) {
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return;
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}
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return {
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node: specifier,
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messageId: MESSAGE_ID,
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data: {type: 'export'},
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fix: fixExportSpecifier(specifier, context),
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};
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},
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});
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/** @type {import('eslint').Rule.RuleModule} */
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const config = {
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create,
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meta: {
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type: 'suggestion',
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docs: {
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description: 'Disallow named usage of default import and export.',
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recommended: true,
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},
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fixable: 'code',
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messages,
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},
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};
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export default config;

‎rules/prefer-export-from.js

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import {isCommaToken, isOpeningBraceToken, isClosingBraceToken} from '@eslint-community/eslint-utils';
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import {isOpeningBraceToken} from '@eslint-community/eslint-utils';
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import {isStringLiteral} from './ast/index.js';
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import {removeSpecifier} from './fix/index.js';
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const MESSAGE_ID_ERROR = 'error';
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const MESSAGE_ID_SUGGESTION = 'suggestion';
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const isTypeImport = specifier => specifier.importKind === 'type' || specifier.parent.importKind === 'type';
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function * removeSpecifier(node, fixer, sourceCode) {
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const {parent} = node;
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const {specifiers} = parent;
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if (specifiers.length === 1) {
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yield * removeImportOrExport(parent, fixer, sourceCode);
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return;
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}
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switch (node.type) {
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case 'ImportSpecifier': {
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const hasOtherSpecifiers = specifiers.some(specifier => specifier !== node && specifier.type === node.type);
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if (!hasOtherSpecifiers) {
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const closingBraceToken = sourceCode.getTokenAfter(node, isClosingBraceToken);
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// If there are other specifiers, they have to be the default import specifier
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// And the default import has to write before the named import specifiers
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// So there must be a comma before
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const commaToken = sourceCode.getTokenBefore(node, isCommaToken);
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yield fixer.replaceTextRange([commaToken.range[0], closingBraceToken.range[1]], '');
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return;
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}
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// Fallthrough
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}
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case 'ExportSpecifier':
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case 'ImportNamespaceSpecifier':
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case 'ImportDefaultSpecifier': {
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yield fixer.remove(node);
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const tokenAfter = sourceCode.getTokenAfter(node);
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if (isCommaToken(tokenAfter)) {
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yield fixer.remove(tokenAfter);
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}
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break;
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}
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// No default
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}
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}
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function * removeImportOrExport(node, fixer, sourceCode) {
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switch (node.type) {
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case 'ImportSpecifier':

‎test/no-named-default.js

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import outdent from 'outdent';
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import {getTester, parsers} from './utils/test.js';
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const {test} = getTester(import.meta);
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// Imports
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test.snapshot({
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valid: [
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'import named from "foo";',
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'import "foo";',
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'import * as named from "foo";',
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...[
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'import type {default as named} from "foo";',
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'import {type default as named} from "foo";',
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].map(code => ({code, languageOptions: {parser: parsers.typescript}})),
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],
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invalid: [
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'import {default as named} from "foo";',
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'import {default as named,} from "foo";',
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'import {default as named, bar} from "foo";',
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'import {default as named, bar,} from "foo";',
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'import defaultExport, {default as named} from "foo";',
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'import defaultExport, {default as named,} from "foo";',
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'import defaultExport, {default as named, bar} from "foo";',
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'import defaultExport, {default as named, bar,} from "foo";',
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'import{default as named}from"foo";',
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'import {default as named}from"foo";',
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'import{default as named} from"foo";',
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'import{default as named,}from"foo";',
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'import/*comment*/{default as named}from"foo";',
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'import /*comment*/{default as named}from"foo";',
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'import{default as named}/*comment*/from"foo";',
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'import defaultExport,{default as named}from "foo";',
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'import defaultExport, {default as named} from "foo" with {type: "json"};',
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'import defaultExport, {default as named} from "foo" with {type: "json"}',
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'import {default as named1, default as named2,} from "foo";',
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],
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});
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// Exports
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test.snapshot({
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valid: [
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'export {foo as default} from "foo";',
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'export * as default from "foo";',
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...[
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'export type {foo as default};',
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'export {type foo as default};',
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].map(code => ({code, languageOptions: {parser: parsers.typescript}})),
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],
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invalid: [
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...[
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'export {foo as default};',
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'export {foo as default,};',
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'export {foo as default, bar};',
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'export {foo as default, bar,};',
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'export{foo as default};',
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].map(code => outdent`
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const foo = 1, bar = 2;
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${code}
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`),
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// Invalid, but typescript allow
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...[
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'export{foo as default, bar as default};',
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outdent`
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export default foo;
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export {foo as default};
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`,
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outdent`
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export default bar;
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export {foo as default};
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`,
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].map(code => ({
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code,
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languageOptions: {parser: parsers.typescript},
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})),
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],
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});

‎test/package.js

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'consistent-existence-index-check',
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'prefer-global-this',
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'no-instanceof-builtin-object',
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'no-named-default',
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'consistent-assert',
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'no-accessor-recursion',
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]);

‎test/snapshots/no-named-default.js.md

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‎test/snapshots/no-named-default.js.snap

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