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noOctalEscape

src/content/docs/linter/rules/no-octal-escape.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: `v1.9.3` - Diagnostic Category: [`lint/suspicious/noOctalEscape`](/reference/diagnostics#diagnostic-category) - This rule is **recommended**, meaning it is enabled by default. - This rule has a [**safe**](/linter/#safe-fixes) fix. - The default severity of this rule is [**warning**](/reference/diagnostics#warning). - Sources: - Same as [`no-octal-escape`](https://eslint.org/docs/latest/rules/no-octal-escape)

How to configure

json
{
	"linter": {
		"rules": {
			"suspicious": {
				"noOctalEscape": "error"
			}
		}
	}
}

Description

Disallow octal escape sequences in string literals

As of the ECMAScript 5 specification, octal escape sequences in string literals are deprecated and should not be used. Unicode escape sequences should be used instead.

Examples

Invalid

js
const foo = "Copyright \251";
<pre class="language-text"><code class="language-text">code-block.js:1:24 <a href="https://biomejs.dev/linter/rules/no-octal-escape">lint/suspicious/noOctalEscape</a> <span style="color: #000; background-color: #ddd;"> FIXABLE </span> ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ <strong><span style="color: Orange;">⚠</span></strong> <span style="color: Orange;">Don't use deprecated </span><span style="color: Orange;"><strong>octal escape sequences</strong></span><span style="color: Orange;">.</span> <strong><span style="color: Tomato;">&gt;</span></strong> <strong>1 │ </strong>const foo = &quot;Copyright &#92;251&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><span style="color: Tomato;">^</span></strong> <strong>2 │ </strong> <strong><span style="color: lightgreen;">ℹ</span></strong> <span style="color: lightgreen;">Safe fix</span><span style="color: lightgreen;">: </span><span style="color: lightgreen;">Use hexadecimal escape sequences instead.</span> <strong>1</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;">t</span><span style="color: Tomato;"><span style="opacity: 0.8;">·</span></span><span style="color: Tomato;">f</span><span style="color: Tomato;">o</span><span style="color: Tomato;">o</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;">C</span><span style="color: Tomato;">o</span><span style="color: Tomato;">p</span><span style="color: Tomato;">y</span><span style="color: Tomato;">r</span><span style="color: Tomato;">i</span><span style="color: Tomato;">g</span><span style="color: Tomato;">h</span><span style="color: Tomato;">t</span><span style="color: Tomato;"><span style="opacity: 0.8;">·</span></span><span style="color: Tomato;">&#92;</span><span style="color: Tomato;"><strong>2</strong></span><span style="color: Tomato;"><strong>5</strong></span><span style="color: Tomato;"><strong>1</strong></span><span style="color: Tomato;">&quot;</span><span style="color: Tomato;">;</span> <strong>1</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;">t</span><span style="color: MediumSeaGreen;"><span style="opacity: 0.8;">·</span></span><span style="color: MediumSeaGreen;">f</span><span style="color: MediumSeaGreen;">o</span><span style="color: MediumSeaGreen;">o</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;">C</span><span style="color: MediumSeaGreen;">o</span><span style="color: MediumSeaGreen;">p</span><span style="color: MediumSeaGreen;">y</span><span style="color: MediumSeaGreen;">r</span><span style="color: MediumSeaGreen;">i</span><span style="color: MediumSeaGreen;">g</span><span style="color: MediumSeaGreen;">h</span><span style="color: MediumSeaGreen;">t</span><span style="color: MediumSeaGreen;"><span style="opacity: 0.8;">·</span></span><span style="color: MediumSeaGreen;">&#92;</span><span style="color: MediumSeaGreen;"><strong>x</strong></span><span style="color: MediumSeaGreen;"><strong>a</strong></span><span style="color: MediumSeaGreen;"><strong>9</strong></span><span style="color: MediumSeaGreen;">&quot;</span><span style="color: MediumSeaGreen;">;</span> <strong>2</strong> <strong>2</strong><strong> │ </strong> </code></pre>

Valid

js
const foo = "Copyright \u00A9"; // unicode escape
const bar = "Copyright \xA9"; // hexadecimal escape
</TabItem> </Tabs>