useConsistentTypeDefinitions

TypeScript and TSX

Caution

This rule is part of the nursery group. This means that it is experimental and the behavior can change at any time.

Summary

• Rule available since: v2.1.4
• Diagnostic Category: lint/nursery/useConsistentTypeDefinitions
• This rule has an unsafe fix.
• The default severity of this rule is information.
• Sources:
  • Same as @typescript-eslint/consistent-type-definitions

How to configure

biome.json

{
  "linter": {
    "rules": {
      "nursery": {
        "useConsistentTypeDefinitions": "error"
      }
    }
  }
}

Description

Enforce type definitions to consistently use either interface or type.

TypeScript provides two different ways to define an object type: interface and type.

This rule enforces consistent usage of either interface or type for object type definitions. Consistent type definition styles, aside from improving code readability, help minimize cognitive load when developers switch between different codebases or within a large codebase.

Example

Invalid

type Point = { x: number; y: number; };
<pre class="language-text"><code class="language-text">code-block.ts:1:1 <a href="https://biomejs.dev/linter/rules/use-consistent-type-definitions">lint/nursery/useConsistentTypeDefinitions</a> <span style="color: #000; background-color: #ddd;"> FIXABLE </span> ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━<br /><br />  <strong><span style="color: lightgreen;">ℹ</span></strong> <span style="color: lightgreen;">Use of the </span><span style="color: lightgreen;"><strong>type</strong></span><span style="color: lightgreen;"> detected.</span><br />  <br />  <strong><span style="color: Tomato;">&gt;</span></strong> <strong>1 │ </strong>type Point = &#123; x: number; y: number; &#125;;<br />   <strong>   │ </strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><br />    <strong>2 │ </strong><br />  <br />  <strong><span style="color: lightgreen;">ℹ</span></strong> <span style="color: lightgreen;">The codebase should use a consistent coding style for the definition of types. This improves the readability and consistency.</span><br />  <br />  <strong><span style="color: lightgreen;">ℹ</span></strong> <span style="color: lightgreen;">Unsafe fix</span><span style="color: lightgreen;">: </span><span style="color: lightgreen;">Use </span><span style="color: lightgreen;"><strong>interface</strong></span><span style="color: lightgreen;">.</span><br />  <br />    <strong>1</strong>  <strong> │ </strong><span style="color: Tomato;">-</span> <span style="color: Tomato;"><strong>t</strong></span><span style="color: Tomato;"><strong>y</strong></span><span style="color: Tomato;"><strong>p</strong></span><span style="color: Tomato;"><strong>e</strong></span><span style="color: Tomato;"><span style="opacity: 0.8;">·</span></span><span style="color: Tomato;">P</span><span style="color: Tomato;">o</span><span style="color: Tomato;">i</span><span style="color: Tomato;">n</span><span style="color: Tomato;">t</span><span style="color: Tomato;"><span style="opacity: 0.8;"><strong>·</strong></span></span><span style="color: Tomato;"><strong>=</strong></span><span style="color: Tomato;"><span style="opacity: 0.8;">·</span></span><span style="color: Tomato;">&#123;</span><span style="color: Tomato;"><span style="opacity: 0.8;"><strong>·</strong></span></span><span style="color: Tomato;">x</span><span style="color: Tomato;">:</span><span style="color: Tomato;"><span style="opacity: 0.8;">·</span></span><span style="color: Tomato;">n</span><span style="color: Tomato;">u</span><span style="color: Tomato;">m</span><span style="color: Tomato;">b</span><span style="color: Tomato;">e</span><span style="color: Tomato;">r</span><span style="color: Tomato;">;</span><span style="color: Tomato;"><span style="opacity: 0.8;"><strong>·</strong></span></span><span style="color: Tomato;">y</span><span style="color: Tomato;">:</span><span style="color: Tomato;"><span style="opacity: 0.8;">·</span></span><span style="color: Tomato;">n</span><span style="color: Tomato;">u</span><span style="color: Tomato;">m</span><span style="color: Tomato;">b</span><span style="color: Tomato;">e</span><span style="color: Tomato;">r</span><span style="color: Tomato;">;</span><span style="color: Tomato;"><span style="opacity: 0.8;"><strong>·</strong></span></span><span style="color: Tomato;">&#125;</span><span style="color: Tomato;"><strong>;</strong></span><br />      <strong>1</strong><strong> │ </strong><span style="color: MediumSeaGreen;">+</span> <span style="color: MediumSeaGreen;"><strong>i</strong></span><span style="color: MediumSeaGreen;"><strong>n</strong></span><span style="color: MediumSeaGreen;"><strong>t</strong></span><span style="color: MediumSeaGreen;"><strong>e</strong></span><span style="color: MediumSeaGreen;"><strong>r</strong></span><span style="color: MediumSeaGreen;"><strong>f</strong></span><span style="color: MediumSeaGreen;"><strong>a</strong></span><span style="color: MediumSeaGreen;"><strong>c</strong></span><span style="color: MediumSeaGreen;"><strong>e</strong></span><span style="color: MediumSeaGreen;"><span style="opacity: 0.8;">·</span></span><span style="color: MediumSeaGreen;">P</span><span style="color: MediumSeaGreen;">o</span><span style="color: MediumSeaGreen;">i</span><span style="color: MediumSeaGreen;">n</span><span style="color: MediumSeaGreen;">t</span><span style="color: MediumSeaGreen;"><span style="opacity: 0.8;">·</span></span><span style="color: MediumSeaGreen;">&#123;</span><br />      <strong>2</strong><strong> │ </strong><span style="color: MediumSeaGreen;">+</span> <span style="color: MediumSeaGreen;"><span style="opacity: 0.8;"><strong>·</strong></span></span><span style="color: MediumSeaGreen;"><span style="opacity: 0.8;"><strong>·</strong></span></span><span style="color: MediumSeaGreen;"><span style="opacity: 0.8;"><strong>·</strong></span></span><span style="color: MediumSeaGreen;"><span style="opacity: 0.8;"><strong>·</strong></span></span><span style="color: MediumSeaGreen;">x</span><span style="color: MediumSeaGreen;">:</span><span style="color: MediumSeaGreen;"><span style="opacity: 0.8;">·</span></span><span style="color: MediumSeaGreen;">n</span><span style="color: MediumSeaGreen;">u</span><span style="color: MediumSeaGreen;">m</span><span style="color: MediumSeaGreen;">b</span><span style="color: MediumSeaGreen;">e</span><span style="color: MediumSeaGreen;">r</span><span style="color: MediumSeaGreen;">;</span><br />      <strong>3</strong><strong> │ </strong><span style="color: MediumSeaGreen;">+</span> <span style="color: MediumSeaGreen;"><span style="opacity: 0.8;"><strong>·</strong></span></span><span style="color: MediumSeaGreen;"><span style="opacity: 0.8;"><strong>·</strong></span></span><span style="color: MediumSeaGreen;"><span style="opacity: 0.8;"><strong>·</strong></span></span><span style="color: MediumSeaGreen;"><span style="opacity: 0.8;"><strong>·</strong></span></span><span style="color: MediumSeaGreen;">y</span><span style="color: MediumSeaGreen;">:</span><span style="color: MediumSeaGreen;"><span style="opacity: 0.8;">·</span></span><span style="color: MediumSeaGreen;">n</span><span style="color: MediumSeaGreen;">u</span><span style="color: MediumSeaGreen;">m</span><span style="color: MediumSeaGreen;">b</span><span style="color: MediumSeaGreen;">e</span><span style="color: MediumSeaGreen;">r</span><span style="color: MediumSeaGreen;">;</span><br />      <strong>4</strong><strong> │ </strong><span style="color: MediumSeaGreen;">+</span> <span style="color: MediumSeaGreen;">&#125;</span><br />    <strong>2</strong> <strong>5</strong><strong> │ </strong>  <br />  <br /></code></pre>

Valid

interface Point {
  x: number;
  y: number;
}

Options

The following options are available

style

This option will determine which style to use for type definitions.

Default: interface

biome.json

{
  "linter": {
    "rules": {
      "nursery": {
        "useConsistentTypeDefinitions": {
          "options": {
            "style": "type"
          }
        }
      }
    }
  }
}

interface Point {
  x: number;
  y: number;
}
<pre class="language-text"><code class="language-text"></code></pre>

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