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noEmptyTypeParameters

src/content/docs/linter/rules/no-empty-type-parameters.mdx

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import { Tabs, TabItem } from '@astrojs/starlight/components';

<Tabs> <TabItem label="TypeScript and TSX" icon="seti:typescript"> ## Summary - Rule available since: `v1.5.0` - Diagnostic Category: [`lint/complexity/noEmptyTypeParameters`](/reference/diagnostics#diagnostic-category) - This rule is **recommended**, meaning it is enabled by default. - This rule doesn't have a fix. - The default severity of this rule is [**warning**](/reference/diagnostics#warning). ## How to configure ```json title="biome.json" { "linter": { "rules": { "complexity": { "noEmptyTypeParameters": "error" } } } } 
## Description
Disallow empty type parameters in type aliases and interfaces.

TypeScript permits the use of empty type parameter lists in type alias and interface declarations; however, this practice is generally discouraged.
Allowing empty type parameter lists can lead to unclear or ambiguous code, where the intention of the generic type is not self-evident.
This rule disallows empty type parameter lists in type alias and interface declarations.

## Examples

### Invalid

```ts
interface Foo<> {}
<pre class="language-text"><code class="language-text">code-block.ts:1:14 <a href="https://biomejs.dev/linter/rules/no-empty-type-parameters">lint/complexity/noEmptyTypeParameters</a> ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ <strong><span style="color: Orange;">⚠</span></strong> <span style="color: Orange;">Using an </span><span style="color: Orange;"><strong>empty type parameter list</strong></span><span style="color: Orange;"> is confusing.</span> <strong><span style="color: Tomato;">&gt;</span></strong> <strong>1 │ </strong>interface Foo&lt;&gt; &#123;&#125; <strong> │ </strong> <strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong> <strong>2 │ </strong> <strong><span style="color: lightgreen;">ℹ</span></strong> <span style="color: lightgreen;">Remove the empty type parameter list or add a type parameter.</span> </code></pre>
ts
type Bar<> = {};
<pre class="language-text"><code class="language-text">code-block.ts:1:9 <a href="https://biomejs.dev/linter/rules/no-empty-type-parameters">lint/complexity/noEmptyTypeParameters</a> ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ <strong><span style="color: Orange;">⚠</span></strong> <span style="color: Orange;">Using an </span><span style="color: Orange;"><strong>empty type parameter list</strong></span><span style="color: Orange;"> is confusing.</span> <strong><span style="color: Tomato;">&gt;</span></strong> <strong>1 │ </strong>type Bar&lt;&gt; = &#123;&#125;; <strong> │ </strong> <strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong> <strong>2 │ </strong> <strong><span style="color: lightgreen;">ℹ</span></strong> <span style="color: lightgreen;">Remove the empty type parameter list or add a type parameter.</span> </code></pre>

Valid

ts
interface Foo {}
ts
type Foo<T> = {
 bar: T;
}
</TabItem> </Tabs>