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# import/no-duplicates Reports if a resolved path is imported more than once. +(fixable) The `--fix` option on the [command line] automatically fixes some problems reported by this rule. ESLint core has a similar rule ([`no-duplicate-imports`](https://eslint.org/docs/rules/no-duplicate-imports)), but this version is different in two key ways: 1. the paths in the source code don't have to exactly match, they just have to point to the same module on the filesystem. (i.e. `./foo` and `./foo.js`) 2. this version distinguishes Flow `type` imports from standard imports. ([#334](https://github.com/import-js/eslint-plugin-import/pull/334)) ## Rule Details Valid: ```js import SomeDefaultClass, * as names from './mod' // Flow `type` import from same module is fine import type SomeType from './mod' ``` ...whereas here, both `./mod` imports will be reported: ```js import SomeDefaultClass from './mod' // oops, some other import separated these lines import foo from './some-other-mod' import * as names from './mod' // will catch this too, assuming it is the same target module import { something } from './mod.js' ``` The motivation is that this is likely a result of two developers importing different names from the same module at different times (and potentially largely different locations in the file.) This rule brings both (or n-many) to attention. ### Query Strings By default, this rule ignores query strings (i.e. paths followed by a question mark), and thus imports from `./mod?a` and `./mod?b` will be considered as duplicates. However you can use the option `considerQueryString` to handle them as different (primarily because browsers will resolve those imports differently). Config: ```json "import/no-duplicates": ["error", {"considerQueryString": true}] ``` And then the following code becomes valid: ```js import minifiedMod from './mod?minify' import noCommentsMod from './mod?comments=0' import originalMod from './mod' ``` It will still catch duplicates when using the same module and the exact same query string: ```js import SomeDefaultClass from './mod?minify' // This is invalid, assuming `./mod` and `./mod.js` are the same target: import * from './mod.js?minify' ``` ## When Not To Use It If the core ESLint version is good enough (i.e. you're _not_ using Flow and you _are_ using [`import/extensions`](./extensions.md)), keep it and don't use this. If you like to split up imports across lines or may need to import a default and a namespace, you may not want to enable this rule.