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), but this version
is different in two key ways:
./foo and ./foo.js)type imports from standard imports. (#334)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.
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'
```
If the core ESLint version is good enough (i.e. you're not using Flow and you are using import/extensions), 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.