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noShoutyConstants

src/content/docs/linter/rules/no-shouty-constants.mdx

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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/style/noShoutyConstants`](/reference/diagnostics#diagnostic-category) - This rule isn't recommended, so you need to enable it. - This rule has an [**unsafe**](/linter/#unsafe-fixes) fix. - The default severity of this rule is [**information**](/reference/diagnostics#information). ## How to configure ```json title="biome.json" { "linter": { "rules": { "style": { "noShoutyConstants": "error" } } } }

## Description
Disallow the use of constants which its value is the upper-case version of its name.

## Examples

### Invalid

```js
const FOO = "FOO";
console.log(FOO);

<pre class="language-text"><code class="language-text">code-block.js:1:7 <a href="https://biomejs.dev/linter/rules/no-shouty-constants">lint/style/noShoutyConstants</a> <span style="color: #000; background-color: #ddd;"> FIXABLE </span> ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ <strong><span style="color: lightgreen;">ℹ</span></strong> <span style="color: lightgreen;">Redundant constant declaration.</span> <strong><span style="color: Tomato;">></span></strong> <strong>1 │ </strong>const FOO = "FOO"; <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>2 │ </strong>console.log(FOO); <strong>3 │ </strong> <strong><span style="color: lightgreen;">ℹ</span></strong> <span style="color: lightgreen;">Used here.</span> <strong>1 │ </strong>const FOO = "FOO"; <strong><span style="color: Tomato;">></span></strong> <strong>2 │ </strong>console.log(FOO); <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> <strong><span style="color: lightgreen;">ℹ</span></strong> <span style="color: lightgreen;">You should avoid declaring constants with a string that's the same </span> <span style="color: lightgreen;"> value as the variable name. It introduces a level of unnecessary </span> <span style="color: lightgreen;"> indirection when it's only two additional characters to inline.</span> <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 the constant value directly</span> <strong>1</strong> <strong> │ </strong><span style="color: Tomato;">-</span> <span style="color: Tomato;"><strong>c</strong></span><span style="color: Tomato;"><strong>o</strong></span><span style="color: Tomato;"><strong>n</strong></span><span style="color: Tomato;"><strong>s</strong></span><span style="color: Tomato;"><strong>t</strong></span><span style="color: Tomato;"><span style="opacity: 0.8;"><strong>·</strong></span></span><span style="color: Tomato;"><strong>F</strong></span><span style="color: Tomato;"><strong>O</strong></span><span style="color: Tomato;"><strong>O</strong></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;"><strong>·</strong></span></span><span style="color: Tomato;"><strong>"</strong></span><span style="color: Tomato;"><strong>F</strong></span><span style="color: Tomato;"><strong>O</strong></span><span style="color: Tomato;"><strong>O</strong></span><span style="color: Tomato;"><strong>"</strong></span><span style="color: Tomato;"><strong>;</strong></span> <strong>2</strong> <strong> │ </strong><span style="color: Tomato;">-</span> <span style="color: Tomato;">c</span><span style="color: Tomato;">o</span><span style="color: Tomato;">n</span><span style="color: Tomato;">s</span><span style="color: Tomato;">o</span><span style="color: Tomato;">l</span><span style="color: Tomato;">e</span><span style="color: Tomato;">.</span><span style="color: Tomato;">l</span><span style="color: Tomato;">o</span><span style="color: Tomato;">g</span><span style="color: Tomato;">(</span><span style="color: Tomato;">F</span><span style="color: Tomato;">O</span><span style="color: Tomato;">O</span><span style="color: Tomato;">)</span><span style="color: Tomato;">;</span> <strong>1</strong><strong> │ </strong><span style="color: MediumSeaGreen;">+</span> <strong>2</strong><strong> │ </strong><span style="color: MediumSeaGreen;">+</span> <span style="color: MediumSeaGreen;">c</span><span style="color: MediumSeaGreen;">o</span><span style="color: MediumSeaGreen;">n</span><span style="color: MediumSeaGreen;">s</span><span style="color: MediumSeaGreen;">o</span><span style="color: MediumSeaGreen;">l</span><span style="color: MediumSeaGreen;">e</span><span style="color: MediumSeaGreen;">.</span><span style="color: MediumSeaGreen;">l</span><span style="color: MediumSeaGreen;">o</span><span style="color: MediumSeaGreen;">g</span><span style="color: MediumSeaGreen;">(</span><span style="color: MediumSeaGreen;"><strong>"</strong></span><span style="color: MediumSeaGreen;">F</span><span style="color: MediumSeaGreen;">O</span><span style="color: MediumSeaGreen;">O</span><span style="color: MediumSeaGreen;"><strong>"</strong></span><span style="color: MediumSeaGreen;">)</span><span style="color: MediumSeaGreen;">;</span> <strong>3</strong> <strong>3</strong><strong> │ </strong> </code></pre>

Valid

js

let FOO = "FOO";
console.log(FOO);

js

export const FOO = "FOO";
console.log(FOO);

js

function f(FOO = "FOO") {
    return FOO;
}

</TabItem> </Tabs>