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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,62 @@ | ||
| # group-exports | ||
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| Reports when multiple named exports or CommonJS assignments are present in a single file and when the default export is not adjacent to the named export. | ||
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| **Rationale:** An `export` declaration or `module.exports` assignment can appear anywhere in the code. By requiring a single export declaration along with the default export being placed next to the named export, your exports will remain at one place, making it easier to see what exports a module provides. | ||
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| ## Rule Details | ||
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| This rule warns whenever a single file contains multiple named exports or assignments to `module.exports` (or `exports`) and when the default export is not adjacent to the named export. | ||
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| ### Valid | ||
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| ```js | ||
| // Default export is adjacent to named export -> ok | ||
| export default function test() {} | ||
| // A single named export -> ok | ||
| export const valid = true | ||
| ``` | ||
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| ```js | ||
| const first = true | ||
| const second = true | ||
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| // A single named export -> ok | ||
| export { | ||
| first, | ||
| second, | ||
| } | ||
| ``` | ||
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| ```js | ||
| // A single exports assignment -> ok | ||
| module.exports = { | ||
| first: true, | ||
| second: true | ||
| } | ||
| ``` | ||
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| ### Invalid | ||
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| ```js | ||
| // Multiple named exports -> not ok! | ||
| export const first = true | ||
| export const second = true | ||
| ``` | ||
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| ```js | ||
| // Default export is not adjacent to the named export -> not ok! | ||
| export default {} | ||
| const first = true | ||
| export { first } | ||
| ``` | ||
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| ```js | ||
| // Multiple exports assignments -> not ok! | ||
| exports.first = true | ||
| exports.second = true | ||
| ``` | ||
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| ## When Not To Use It | ||
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| If you do not mind having your exports spread across the file, you can safely turn this rule off. |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,105 @@ | ||
| const meta = {} | ||
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| /** | ||
| * Return an error message based on what node type caused the rule to warn | ||
| * | ||
| * @param {string} forType The node's type for which to return the error message | ||
| * @return {String} The error message to be displayed to the user | ||
| * @private | ||
| */ | ||
| function message(forType) { | ||
| switch (forType) { | ||
| case 'ExportNamedDeclaration': | ||
| return 'Multiple named export declarations' | ||
| case 'ExportDefaultDeclaration': | ||
| return 'Default export declaration should be adjacent to named export' | ||
| case 'MemberExpression': | ||
| return 'Multiple CommonJS exports' | ||
| default: | ||
| throw new Error('Unexpected node type') | ||
| } | ||
| } | ||
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| /** | ||
| * Check if two nodes are adjacent (only whitespace between them) | ||
| * | ||
| * The two nodes do not have to be sorted in the order they appear in the code. | ||
| * | ||
| * @param {Object} opts Options for the check | ||
| * @param {Object} opts.context The context of the nodes | ||
| * @param {Object} opts.first The first node | ||
| * @param {Object} opts.second The second node | ||
| * @return {Boolean} | ||
| * @private | ||
| */ | ||
| function isAdjacent(opts = {}) { | ||
| const sourceCode = opts.context.getSourceCode() | ||
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| if (sourceCode.getTokensBetween(opts.first, opts.second).length || | ||
| sourceCode.getTokensBetween(opts.second, opts.first).length) { | ||
| return false | ||
| } | ||
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| return true | ||
| } | ||
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| function create(context) { | ||
| const exports = { | ||
| named: new Set(), | ||
| default: null, | ||
| last: null, | ||
| } | ||
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| return { | ||
| ExportDefaultDeclaration(node) { | ||
| exports.default = node | ||
| }, | ||
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| ExportNamedDeclaration(node) { | ||
| exports.named.add(node) | ||
| exports.last = node | ||
| }, | ||
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| MemberExpression(node) { | ||
| if (node.object.name === 'module' && node.property.name === 'exports') { | ||
| exports.named.add(node) | ||
| } | ||
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| if (node.object.name === 'exports') { | ||
| exports.named.add(node) | ||
| } | ||
| }, | ||
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| 'Program:exit': function onExit() { | ||
| if (exports.named.size > 1) { | ||
| for (const node of exports.named) { | ||
| context.report({ | ||
| node, | ||
| message: message(node.type), | ||
| }) | ||
| } | ||
| } | ||
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| // There is exactly one named export and a default export -> check if they are adjacent | ||
| if (exports.default && exports.last && exports.named.size === 1) { | ||
| const adjacent = isAdjacent({ | ||
| context, | ||
| first: exports.default, | ||
| second: exports.last, | ||
| }) | ||
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| if (!adjacent) { | ||
| context.report({ | ||
| node: exports.default, | ||
| message: message(exports.default.type), | ||
| }) | ||
| } | ||
| } | ||
| }, | ||
| } | ||
| } | ||
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| export default { | ||
| meta, | ||
| create, | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,70 @@ | ||
| import { test } from '../utils' | ||
| import { RuleTester } from 'eslint' | ||
| import rule from 'rules/group-exports' | ||
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| const ruleTester = new RuleTester() | ||
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| ruleTester.run('group-exports', rule, { | ||
| valid: [ | ||
| test({ code: 'export const test = true' }), | ||
| test({ code: 'export default {}\nexport const test = true' }), | ||
| test({ code: [ | ||
| 'const first = true', | ||
| 'const second = true', | ||
| 'export { first,\nsecond }', | ||
| ].join('\n') }), | ||
| test({ code: 'export default {}\n/* test */\nexport const test = true'}), | ||
| test({ code: 'export default {}\n// test\nexport const test = true'}), | ||
| test({ code: 'export const test = true\n/* test */\nexport default {}'}), | ||
| test({ code: 'export const test = true\n// test\nexport default {}'}), | ||
| test({ code: 'module.exports = {} '}), | ||
| test({ code: 'module.exports = { test: true,\nanother: false }' }), | ||
| test({ code: 'exports.test = true' }), | ||
| ], | ||
| invalid: [ | ||
| test({ | ||
| code: [ | ||
| 'export const test = true', | ||
| 'export const another = true', | ||
| ].join('\n'), | ||
| errors: [ | ||
| 'Multiple named export declarations', | ||
| 'Multiple named export declarations', | ||
| ], | ||
| }), | ||
| test({ | ||
| code: [ | ||
| 'module.exports = {}', | ||
| 'module.exports.test = true', | ||
| 'module.exports.another = true', | ||
| ].join('\n'), | ||
| errors: [ | ||
| 'Multiple CommonJS exports', | ||
| 'Multiple CommonJS exports', | ||
| 'Multiple CommonJS exports', | ||
| ], | ||
| }), | ||
| test({ | ||
| code: [ | ||
| 'module.exports = {}', | ||
| 'module.exports = {}', | ||
| ].join('\n'), | ||
| errors: [ | ||
| 'Multiple CommonJS exports', | ||
| 'Multiple CommonJS exports', | ||
| ], | ||
| }), | ||
| test({ | ||
| code: 'export default {}\nconst test = true\nexport { test }', | ||
| errors: [ | ||
| 'Default export declaration should be adjacent to named export', | ||
| ], | ||
| }), | ||
| test({ | ||
| code: 'const test = true\nexport { test }\nconst another = true\nexport default {}', | ||
| errors: [ | ||
| 'Default export declaration should be adjacent to named export', | ||
| ], | ||
| }), | ||
| ], | ||
| }) |