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useHtmlLang

src/content/docs/linter/rules/use-html-lang.mdx

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

<Tabs> <TabItem label="JSX and TSX" icon="seti:javascript"> ## Summary - Rule available since: `v1.0.0` - Diagnostic Category: [`lint/a11y/useHtmlLang`](/reference/diagnostics#diagnostic-category) - This rule is **recommended**, meaning it is enabled by default. - This rule doesn't have a fix. - The default severity of this rule is [**error**](/reference/diagnostics#error). - Sources: - Same as [`jsx-a11y/html-has-lang`](https://github.com/jsx-eslint/eslint-plugin-jsx-a11y/blob/main/docs/rules/html-has-lang.md)

How to configure

json
{
	"linter": {
		"rules": {
			"a11y": {
				"useHtmlLang": "error"
			}
		}
	}
}

Description

Enforce that html element has lang attribute.

Examples

Invalid

jsx
<html></html>
<pre class="language-text"><code class="language-text">code-block.jsx:1:1 <a href="https://biomejs.dev/linter/rules/use-html-lang">lint/a11y/useHtmlLang</a> ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ <strong><span style="color: Tomato;">✖</span></strong> <span style="color: Tomato;">Provide a </span><span style="color: Tomato;"><strong>lang</strong></span><span style="color: Tomato;"> attribute when using the </span><span style="color: Tomato;"><strong>html</strong></span><span style="color: Tomato;"> element.</span> <strong><span style="color: Tomato;">&gt;</span></strong> <strong>1 │ </strong>&lt;html&gt;&lt;/html&gt; <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>2 │ </strong> <strong><span style="color: lightgreen;">ℹ</span></strong> <span style="color: lightgreen;">Setting a </span><span style="color: lightgreen;"><strong>lang</strong></span><span style="color: lightgreen;"> attribute on HTML document elements configures the language used by screen readers when no user default is specified.</span> </code></pre>
jsx
<html lang={""}></html>
<pre class="language-text"><code class="language-text">code-block.jsx:1:1 <a href="https://biomejs.dev/linter/rules/use-html-lang">lint/a11y/useHtmlLang</a> ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ <strong><span style="color: Tomato;">✖</span></strong> <span style="color: Tomato;">Provide a </span><span style="color: Tomato;"><strong>lang</strong></span><span style="color: Tomato;"> attribute when using the </span><span style="color: Tomato;"><strong>html</strong></span><span style="color: Tomato;"> element.</span> <strong><span style="color: Tomato;">&gt;</span></strong> <strong>1 │ </strong>&lt;html lang=&#123;&quot;&quot;&#125;&gt;&lt;/html&gt; <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>2 │ </strong> <strong><span style="color: lightgreen;">ℹ</span></strong> <span style="color: lightgreen;">Setting a </span><span style="color: lightgreen;"><strong>lang</strong></span><span style="color: lightgreen;"> attribute on HTML document elements configures the language used by screen readers when no user default is specified.</span> </code></pre>
jsx
<html lang={null}></html>
<pre class="language-text"><code class="language-text">code-block.jsx:1:1 <a href="https://biomejs.dev/linter/rules/use-html-lang">lint/a11y/useHtmlLang</a> ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ <strong><span style="color: Tomato;">✖</span></strong> <span style="color: Tomato;">Provide a </span><span style="color: Tomato;"><strong>lang</strong></span><span style="color: Tomato;"> attribute when using the </span><span style="color: Tomato;"><strong>html</strong></span><span style="color: Tomato;"> element.</span> <strong><span style="color: Tomato;">&gt;</span></strong> <strong>1 │ </strong>&lt;html lang=&#123;null&#125;&gt;&lt;/html&gt; <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>2 │ </strong> <strong><span style="color: lightgreen;">ℹ</span></strong> <span style="color: lightgreen;">Setting a </span><span style="color: lightgreen;"><strong>lang</strong></span><span style="color: lightgreen;"> attribute on HTML document elements configures the language used by screen readers when no user default is specified.</span> </code></pre>
jsx
<html lang={undefined}></html>
<pre class="language-text"><code class="language-text">code-block.jsx:1:1 <a href="https://biomejs.dev/linter/rules/use-html-lang">lint/a11y/useHtmlLang</a> ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ <strong><span style="color: Tomato;">✖</span></strong> <span style="color: Tomato;">Provide a </span><span style="color: Tomato;"><strong>lang</strong></span><span style="color: Tomato;"> attribute when using the </span><span style="color: Tomato;"><strong>html</strong></span><span style="color: Tomato;"> element.</span> <strong><span style="color: Tomato;">&gt;</span></strong> <strong>1 │ </strong>&lt;html lang=&#123;undefined&#125;&gt;&lt;/html&gt; <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>2 │ </strong> <strong><span style="color: lightgreen;">ℹ</span></strong> <span style="color: lightgreen;">Setting a </span><span style="color: lightgreen;"><strong>lang</strong></span><span style="color: lightgreen;"> attribute on HTML document elements configures the language used by screen readers when no user default is specified.</span> </code></pre>
jsx
<html lang={true}></html>
<pre class="language-text"><code class="language-text">code-block.jsx:1:1 <a href="https://biomejs.dev/linter/rules/use-html-lang">lint/a11y/useHtmlLang</a> ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ <strong><span style="color: Tomato;">✖</span></strong> <span style="color: Tomato;">Provide a </span><span style="color: Tomato;"><strong>lang</strong></span><span style="color: Tomato;"> attribute when using the </span><span style="color: Tomato;"><strong>html</strong></span><span style="color: Tomato;"> element.</span> <strong><span style="color: Tomato;">&gt;</span></strong> <strong>1 │ </strong>&lt;html lang=&#123;true&#125;&gt;&lt;/html&gt; <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>2 │ </strong> <strong><span style="color: lightgreen;">ℹ</span></strong> <span style="color: lightgreen;">Setting a </span><span style="color: lightgreen;"><strong>lang</strong></span><span style="color: lightgreen;"> attribute on HTML document elements configures the language used by screen readers when no user default is specified.</span> </code></pre>

Valid

jsx
<html lang="en"></html>
jsx
<html lang={language}></html>
jsx
<html {...props}></html>
jsx
<html lang={""} {...props}></html>

Accessibility guidelines

</TabItem> <TabItem label="HTML" icon="seti:html"> ## Summary - Rule available since: `v2.4.0` - Diagnostic Category: [`lint/a11y/useHtmlLang`](/reference/diagnostics#diagnostic-category) - This rule is **recommended**, meaning it is enabled by default. - This rule doesn't have a fix. - The default severity of this rule is [**error**](/reference/diagnostics#error). - Sources: - Same as [`jsx-a11y/html-has-lang`](https://github.com/jsx-eslint/eslint-plugin-jsx-a11y/blob/main/docs/rules/html-has-lang.md) - Same as [`@html-eslint/require-lang`](https://html-eslint.org/docs/rules/require-lang)

How to configure

json
{
	"linter": {
		"rules": {
			"a11y": {
				"useHtmlLang": "error"
			}
		}
	}
}

Description

Enforce that html element has lang attribute.

Examples

Invalid

html
<html></html>
<pre class="language-text"><code class="language-text">code-block.html:1:1 <a href="https://biomejs.dev/linter/rules/use-html-lang">lint/a11y/useHtmlLang</a> ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ <strong><span style="color: Tomato;">✖</span></strong> <span style="color: Tomato;">Provide a </span><span style="color: Tomato;"><strong>lang</strong></span><span style="color: Tomato;"> attribute when using the </span><span style="color: Tomato;"><strong>html</strong></span><span style="color: Tomato;"> element.</span> <strong><span style="color: Tomato;">&gt;</span></strong> <strong>1 │ </strong>&lt;html&gt;&lt;/html&gt; <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>2 │ </strong> <strong><span style="color: lightgreen;">ℹ</span></strong> <span style="color: lightgreen;">Setting a </span><span style="color: lightgreen;"><strong>lang</strong></span><span style="color: lightgreen;"> attribute on HTML document elements configures the language used by screen readers when no user default is specified.</span> </code></pre>
html
<html lang=""></html>
<pre class="language-text"><code class="language-text">code-block.html:1:1 <a href="https://biomejs.dev/linter/rules/use-html-lang">lint/a11y/useHtmlLang</a> ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ <strong><span style="color: Tomato;">✖</span></strong> <span style="color: Tomato;">Provide a </span><span style="color: Tomato;"><strong>lang</strong></span><span style="color: Tomato;"> attribute when using the </span><span style="color: Tomato;"><strong>html</strong></span><span style="color: Tomato;"> element.</span> <strong><span style="color: Tomato;">&gt;</span></strong> <strong>1 │ </strong>&lt;html lang=&quot;&quot;&gt;&lt;/html&gt; <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>2 │ </strong> <strong><span style="color: lightgreen;">ℹ</span></strong> <span style="color: lightgreen;">Setting a </span><span style="color: lightgreen;"><strong>lang</strong></span><span style="color: lightgreen;"> attribute on HTML document elements configures the language used by screen readers when no user default is specified.</span> </code></pre>

Valid

html
<html lang="en"></html>

Accessibility guidelines

</TabItem> </Tabs>