ContextQMD
Back to Biomejs

useLiteralKeys

src/content/docs/linter/rules/use-literal-keys.mdx

latest11.9 KB
Original Source

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

<Tabs> <TabItem label="JavaScript (and super languages)" icon="seti:javascript"> ## Summary - Rule available since: `v1.0.0` - Diagnostic Category: [`lint/complexity/useLiteralKeys`](/reference/diagnostics#diagnostic-category) - This rule is **recommended**, meaning it is enabled by default. - This rule has an [**unsafe**](/linter/#unsafe-fixes) fix. - The default severity of this rule is [**information**](/reference/diagnostics#information). - Sources: - Same as [`dot-notation`](https://eslint.org/docs/latest/rules/dot-notation) - Same as [`no-useless-computed-key`](https://eslint.org/docs/latest/rules/no-useless-computed-key) - Same as [`@typescript-eslint/dot-notation`](https://typescript-eslint.io/rules/dot-notation)

How to configure

json
{
	"linter": {
		"rules": {
			"complexity": {
				"useLiteralKeys": "error"
			}
		}
	}
}

Description

Enforce the usage of a literal access to properties over computed property access.

Examples

Invalid

js
a.b["c"];
<pre class="language-text"><code class="language-text">code-block.js:1:5 <a href="https://biomejs.dev/linter/rules/use-literal-keys">lint/complexity/useLiteralKeys</a> <span style="color: #000; background-color: #ddd;"> FIXABLE </span> ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ <strong><span style="color: lightgreen;">ℹ</span></strong> <span style="color: lightgreen;">The computed expression can be simplified without the use of a string literal.</span> <strong><span style="color: Tomato;">&gt;</span></strong> <strong>1 │ </strong>a.b[&quot;c&quot;]; <strong> │ </strong> <strong><span style="color: Tomato;">^</span></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;">Unsafe fix</span><span style="color: lightgreen;">: </span><span style="color: lightgreen;">Use a literal key instead.</span> <strong>1</strong> <strong> │ </strong><span style="color: Tomato;">-</span> <span style="color: Tomato;"><strong>a</strong></span><span style="color: Tomato;"><strong>.</strong></span><span style="color: Tomato;"><strong>b</strong></span><span style="color: Tomato;"><strong>[</strong></span><span style="color: Tomato;"><strong>&quot;</strong></span><span style="color: Tomato;"><strong>c</strong></span><span style="color: Tomato;"><strong>&quot;</strong></span><span style="color: Tomato;"><strong>]</strong></span><span style="color: Tomato;">;</span> <strong>1</strong><strong> │ </strong><span style="color: MediumSeaGreen;">+</span> <span style="color: MediumSeaGreen;"><strong>a</strong></span><span style="color: MediumSeaGreen;"><strong>.</strong></span><span style="color: MediumSeaGreen;"><strong>b</strong></span><span style="color: MediumSeaGreen;"><strong>.</strong></span><span style="color: MediumSeaGreen;"><strong>c</strong></span><span style="color: MediumSeaGreen;">;</span> <strong>2</strong> <strong>2</strong><strong> │ </strong> </code></pre>
js
a.c[`d`]
<pre class="language-text"><code class="language-text">code-block.js:1:5 <a href="https://biomejs.dev/linter/rules/use-literal-keys">lint/complexity/useLiteralKeys</a> <span style="color: #000; background-color: #ddd;"> FIXABLE </span> ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ <strong><span style="color: lightgreen;">ℹ</span></strong> <span style="color: lightgreen;">The computed expression can be simplified without the use of a string literal.</span> <strong><span style="color: Tomato;">&gt;</span></strong> <strong>1 │ </strong>a.c[&#96;d&#96;] <strong> │ </strong> <strong><span style="color: Tomato;">^</span></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;">Unsafe fix</span><span style="color: lightgreen;">: </span><span style="color: lightgreen;">Use a literal key instead.</span> <strong>1</strong> <strong> │ </strong><span style="color: Tomato;">-</span> <span style="color: Tomato;"><strong>a</strong></span><span style="color: Tomato;"><strong>.</strong></span><span style="color: Tomato;"><strong>c</strong></span><span style="color: Tomato;"><strong>[</strong></span><span style="color: Tomato;"><strong>&#96;</strong></span><span style="color: Tomato;"><strong>d</strong></span><span style="color: Tomato;"><strong>&#96;</strong></span><span style="color: Tomato;"><strong>]</strong></span> <strong>1</strong><strong> │ </strong><span style="color: MediumSeaGreen;">+</span> <span style="color: MediumSeaGreen;"><strong>a</strong></span><span style="color: MediumSeaGreen;"><strong>.</strong></span><span style="color: MediumSeaGreen;"><strong>c</strong></span><span style="color: MediumSeaGreen;"><strong>.</strong></span><span style="color: MediumSeaGreen;"><strong>d</strong></span> <strong>2</strong> <strong>2</strong><strong> │ </strong> </code></pre>
js
a.c[`d`] = "something"
<pre class="language-text"><code class="language-text">code-block.js:1:5 <a href="https://biomejs.dev/linter/rules/use-literal-keys">lint/complexity/useLiteralKeys</a> <span style="color: #000; background-color: #ddd;"> FIXABLE </span> ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ <strong><span style="color: lightgreen;">ℹ</span></strong> <span style="color: lightgreen;">The computed expression can be simplified without the use of a string literal.</span> <strong><span style="color: Tomato;">&gt;</span></strong> <strong>1 │ </strong>a.c[&#96;d&#96;] = &quot;something&quot; <strong> │ </strong> <strong><span style="color: Tomato;">^</span></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;">Unsafe fix</span><span style="color: lightgreen;">: </span><span style="color: lightgreen;">Use a literal key instead.</span> <strong>1</strong> <strong> │ </strong><span style="color: Tomato;">-</span> <span style="color: Tomato;"><strong>a</strong></span><span style="color: Tomato;"><strong>.</strong></span><span style="color: Tomato;"><strong>c</strong></span><span style="color: Tomato;"><strong>[</strong></span><span style="color: Tomato;"><strong>&#96;</strong></span><span style="color: Tomato;"><strong>d</strong></span><span style="color: Tomato;"><strong>&#96;</strong></span><span style="color: Tomato;"><strong>]</strong></span><span style="color: Tomato;"><span style="opacity: 0.8;">·</span></span><span style="color: Tomato;">=</span><span style="color: Tomato;"><span style="opacity: 0.8;">·</span></span><span style="color: Tomato;">&quot;</span><span style="color: Tomato;">s</span><span style="color: Tomato;">o</span><span style="color: Tomato;">m</span><span style="color: Tomato;">e</span><span style="color: Tomato;">t</span><span style="color: Tomato;">h</span><span style="color: Tomato;">i</span><span style="color: Tomato;">n</span><span style="color: Tomato;">g</span><span style="color: Tomato;">&quot;</span> <strong>1</strong><strong> │ </strong><span style="color: MediumSeaGreen;">+</span> <span style="color: MediumSeaGreen;"><strong>a</strong></span><span style="color: MediumSeaGreen;"><strong>.</strong></span><span style="color: MediumSeaGreen;"><strong>c</strong></span><span style="color: MediumSeaGreen;"><strong>.</strong></span><span style="color: MediumSeaGreen;"><strong>d</strong></span><span style="color: MediumSeaGreen;"><span style="opacity: 0.8;">·</span></span><span style="color: MediumSeaGreen;">=</span><span style="color: MediumSeaGreen;"><span style="opacity: 0.8;">·</span></span><span style="color: MediumSeaGreen;">&quot;</span><span style="color: MediumSeaGreen;">s</span><span style="color: MediumSeaGreen;">o</span><span style="color: MediumSeaGreen;">m</span><span style="color: MediumSeaGreen;">e</span><span style="color: MediumSeaGreen;">t</span><span style="color: MediumSeaGreen;">h</span><span style="color: MediumSeaGreen;">i</span><span style="color: MediumSeaGreen;">n</span><span style="color: MediumSeaGreen;">g</span><span style="color: MediumSeaGreen;">&quot;</span> <strong>2</strong> <strong>2</strong><strong> │ </strong> </code></pre>
js
a = {
	['b']: d
}
<pre class="language-text"><code class="language-text">code-block.js:2:3 <a href="https://biomejs.dev/linter/rules/use-literal-keys">lint/complexity/useLiteralKeys</a> <span style="color: #000; background-color: #ddd;"> FIXABLE </span> ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ <strong><span style="color: lightgreen;">ℹ</span></strong> <span style="color: lightgreen;">The computed expression can be simplified to a string literal.</span> <strong>1 │ </strong>a = &#123; <strong><span style="color: Tomato;">&gt;</span></strong> <strong>2 │ </strong> ['b']: d <strong> │ </strong> <strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong> <strong>3 │ </strong>&#125; <strong>4 │ </strong> <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 a literal key instead.</span> <strong>1</strong> <strong>1</strong><strong> │ </strong> a = &#123; <strong>2</strong> <strong> │ </strong><span style="color: Tomato;">-</span> <span style="color: Tomato;"><span style="opacity: 0.8;">→ </span></span><span style="color: Tomato;"><strong>[</strong></span><span style="color: Tomato;"><strong>'</strong></span><span style="color: Tomato;">b</span><span style="color: Tomato;"><strong>'</strong></span><span style="color: Tomato;"><strong>]</strong></span><span style="color: Tomato;">:</span><span style="color: Tomato;"><span style="opacity: 0.8;">·</span></span><span style="color: Tomato;">d</span> <strong>2</strong><strong> │ </strong><span style="color: MediumSeaGreen;">+</span> <span style="color: MediumSeaGreen;"><span style="opacity: 0.8;">→ </span></span><span style="color: MediumSeaGreen;"><strong>&quot;</strong></span><span style="color: MediumSeaGreen;">b</span><span style="color: MediumSeaGreen;"><strong>&quot;</strong></span><span style="color: MediumSeaGreen;">:</span><span style="color: MediumSeaGreen;"><span style="opacity: 0.8;">·</span></span><span style="color: MediumSeaGreen;">d</span> <strong>3</strong> <strong>3</strong><strong> │ </strong> &#125; <strong>4</strong> <strong>4</strong><strong> │ </strong> </code></pre>

Valid

js
a["c" + "d"];
a[d.c];
</TabItem> </Tabs>