92 lines
2.8 KiB
Plaintext
92 lines
2.8 KiB
Plaintext
# import/consistent-type-specifier-style
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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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In both Flow and TypeScript you can mark an import as a type-only import by adding a "kind" marker to the import. Both languages support two positions for marker.
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**At the top-level** which marks all names in the import as type-only and applies to named, default, and namespace (for TypeScript) specifiers:
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```ts
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import type Foo from 'Foo';
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import type {Bar} from 'Bar';
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// ts only
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import type * as Bam from 'Bam';
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// flow only
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import typeof Baz from 'Baz';
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```
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**Inline** with to the named import, which marks just the specific name in the import as type-only. An inline specifier is only valid for named specifiers, and not for default or namespace specifiers:
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```ts
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import {type Foo} from 'Foo';
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// flow only
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import {typeof Bar} from 'Bar';
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```
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## Rule Details
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This rule either enforces or bans the use of inline type-only markers for named imports.
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This rule includes a fixer that will automatically convert your specifiers to the correct form - however the fixer will not respect your preferences around de-duplicating imports. If this is important to you, consider using the [`import/no-duplicates`] rule.
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[`import/no-duplicates`]: ./no-duplicates.md
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## Options
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The rule accepts a single string option which may be one of:
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- `'prefer-inline'` - enforces that named type-only specifiers are only ever written with an inline marker; and never as part of a top-level, type-only import.
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- `'prefer-top-level'` - enforces that named type-only specifiers only ever written as part of a top-level, type-only import; and never with an inline marker.
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By default the rule will use the `prefer-inline` option.
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## Examples
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### `prefer-top-level`
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❌ Invalid with `["error", "prefer-top-level"]`
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```ts
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import {type Foo} from 'Foo';
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import Foo, {type Bar} from 'Foo';
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// flow only
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import {typeof Foo} from 'Foo';
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```
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✅ Valid with `["error", "prefer-top-level"]`
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```ts
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import type {Foo} from 'Foo';
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import type Foo, {Bar} from 'Foo';
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// flow only
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import typeof {Foo} from 'Foo';
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```
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### `prefer-inline`
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❌ Invalid with `["error", "prefer-inline"]`
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```ts
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import type {Foo} from 'Foo';
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import type Foo, {Bar} from 'Foo';
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// flow only
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import typeof {Foo} from 'Foo';
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```
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✅ Valid with `["error", "prefer-inline"]`
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```ts
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import {type Foo} from 'Foo';
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import Foo, {type Bar} from 'Foo';
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// flow only
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import {typeof Foo} from 'Foo';
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```
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## When Not To Use It
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If you aren't using Flow or TypeScript 4.5+, then this rule does not apply and need not be used.
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If you don't care about, and don't want to standardize how named specifiers are imported then you should not use this rule.
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