useEnumInitializers

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

<Tabs> <TabItem label="TypeScript and TSX" icon="seti:typescript"> ## Summary - Rule available since: `v1.0.0` - Diagnostic Category: [`lint/style/useEnumInitializers`](/reference/diagnostics#diagnostic-category) - This rule isn't recommended, so you need to enable it. - This rule has a [**safe**](/linter/#safe-fixes) fix. - The default severity of this rule is [**warning**](/reference/diagnostics#warning). - Sources: - Same as [`@typescript-eslint/prefer-enum-initializers`](https://typescript-eslint.io/rules/prefer-enum-initializers)

How to configure

json

{
	"linter": {
		"rules": {
			"style": {
				"useEnumInitializers": "error"
			}
		}
	}
}

Description

Require that each enum member value be explicitly initialized.

TypeScript enums are a practical way to organize semantically related constant values. Members of enums that don't have explicit values are by default given sequentially increasing numbers.

When the value of enum members are important, allowing implicit values for enum members can cause bugs if enum declarations are modified over time.

Examples

Invalid

enum Version {
    V1,
}

<pre class="language-text"><code class="language-text">code-block.ts:1:6 <a href="https://biomejs.dev/linter/rules/use-enum-initializers">lint/style/useEnumInitializers</a> FIXABLE ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ ⚠ This enum declaration contains members that are implicitly initialized. > 1 │ enum Version { │ ^^^^^^^ 2 │ V1, 3 │ } ℹ This enum member should be explicitly initialized. 1 │ enum Version { > 2 │ V1, │ ^^ 3 │ } 4 │ ℹ Allowing implicit initializations for enum members can cause bugs if enum declarations are modified over time. ℹ Safe fix: Initialize all enum members. 2 │ ····V1·=·0, │ ++++ </code></pre>

enum Status {
    Open = 1,
    Close,
}

<pre class="language-text"><code class="language-text">code-block.ts:1:6 <a href="https://biomejs.dev/linter/rules/use-enum-initializers">lint/style/useEnumInitializers</a> FIXABLE ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ ⚠ This enum declaration contains members that are implicitly initialized. > 1 │ enum Status { │ ^^^^^^ 2 │ Open = 1, 3 │ Close, ℹ This enum member should be explicitly initialized. 1 │ enum Status { 2 │ Open = 1, > 3 │ Close, │ ^^^^^ 4 │ } 5 │ ℹ Allowing implicit initializations for enum members can cause bugs if enum declarations are modified over time. ℹ Safe fix: Initialize all enum members. 3 │ ····Close·=·2, │ ++++ </code></pre>

enum Color {
    Red = "Red",
    Green = "Green",
    Blue,
}

<pre class="language-text"><code class="language-text">code-block.ts:1:6 <a href="https://biomejs.dev/linter/rules/use-enum-initializers">lint/style/useEnumInitializers</a> FIXABLE ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ ⚠ This enum declaration contains members that are implicitly initialized. > 1 │ enum Color { │ ^^^^^ 2 │ Red = "Red", 3 │ Green = "Green", ℹ This enum member should be explicitly initialized. 2 │ Red = "Red", 3 │ Green = "Green", > 4 │ Blue, │ ^^^^ 5 │ } 6 │ ℹ Allowing implicit initializations for enum members can cause bugs if enum declarations are modified over time. ℹ Safe fix: Initialize all enum members. 4 │ ····Blue·=·"Blue", │ +++++++++ </code></pre>

Valid

enum Status {
    Open = 1,
    Close = 2,
}

enum Color {
    Red = "Red",
    Green = "Green",
    Blue = "Blue",
}

declare enum Weather {
    Rainy,
    Sunny,
}

</TabItem> </Tabs>

How to configure

Description

Examples

Invalid

Valid

Related links