86 lines
1.5 KiB
Plaintext
86 lines
1.5 KiB
Plaintext
---
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description: 'Disallow type arguments that are equal to the default.'
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---
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import Tabs from '@theme/Tabs';
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import TabItem from '@theme/TabItem';
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> 🛑 This file is source code, not the primary documentation location! 🛑
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>
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> See **https://typescript-eslint.io/rules/no-unnecessary-type-arguments** for documentation.
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Type parameters in TypeScript may specify a default value.
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For example:
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```ts
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function f<T = number>(/* ... */) {
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// ...
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}
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```
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It is redundant to provide an explicit type parameter equal to that default: e.g. calling `f<number>(...)`.
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This rule reports when an explicitly specified type argument is the default for that type parameter.
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## Examples
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<Tabs>
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<TabItem value="❌ Incorrect">
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```ts
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function f<T = number>() {}
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f<number>();
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```
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```ts
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function g<T = number, U = string>() {}
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g<string, string>();
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```
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```ts
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class C<T = number> {}
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new C<number>();
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class D extends C<number> {}
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```
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```ts
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interface I<T = number> {}
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class Impl implements I<number> {}
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```
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</TabItem>
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<TabItem value="✅ Correct">
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```ts
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function f<T = number>() {}
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f();
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f<string>();
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```
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```ts
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function g<T = number, U = string>() {}
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g<string>();
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g<number, number>();
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```
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```ts
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class C<T = number> {}
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new C();
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new C<string>();
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class D extends C {}
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class D extends C<string> {}
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```
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```ts
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interface I<T = number> {}
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class Impl implements I<string> {}
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```
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</TabItem>
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</Tabs>
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## When Not To Use It
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If you prefer explicitly specifying type parameters even when they are equal to the default, you can skip this rule.
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