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noNestedTernary

src/content/docs/linter/rules/no-nested-ternary.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/style/noNestedTernary`](/reference/diagnostics#diagnostic-category) - This rule isn't recommended, so you need to enable it. - This rule doesn't have a fix. - The default severity of this rule is [**information**](/reference/diagnostics#information). - Sources: - Same as [`no-nested-ternary`](https://eslint.org/docs/latest/rules/no-nested-ternary)

How to configure

json
{
	"linter": {
		"rules": {
			"style": {
				"noNestedTernary": "error"
			}
		}
	}
}

Description

Disallow nested ternary expressions.

Nesting ternary expressions can make code more difficult to understand.

Examples

Invalid

js
const thing = foo ? bar : baz === qux ? quxx : foobar;
<pre class="language-text"><code class="language-text">code-block.js:1:27 <a href="https://biomejs.dev/linter/rules/no-nested-ternary">lint/style/noNestedTernary</a> ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ <strong><span style="color: lightgreen;">ℹ</span></strong> <span style="color: lightgreen;">Do not nest ternary expressions.</span> <strong><span style="color: Tomato;">&gt;</span></strong> <strong>1 │ </strong>const thing = foo ? bar : baz === qux ? quxx : foobar; <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><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;">Nesting ternary expressions can make code more difficult to understand.</span> <strong><span style="color: lightgreen;">ℹ</span></strong> <span style="color: lightgreen;">Convert nested ternary expression into if-else statements or separate the conditions to make the logic easier to understand.</span> </code></pre>
js
foo ? baz === qux ? quxx() : foobar() : bar();
<pre class="language-text"><code class="language-text">code-block.js:1:7 <a href="https://biomejs.dev/linter/rules/no-nested-ternary">lint/style/noNestedTernary</a> ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ <strong><span style="color: lightgreen;">ℹ</span></strong> <span style="color: lightgreen;">Do not nest ternary expressions.</span> <strong><span style="color: Tomato;">&gt;</span></strong> <strong>1 │ </strong>foo ? baz === qux ? quxx() : foobar() : bar(); <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><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;">Nesting ternary expressions can make code more difficult to understand.</span> <strong><span style="color: lightgreen;">ℹ</span></strong> <span style="color: lightgreen;">Convert nested ternary expression into if-else statements or separate the conditions to make the logic easier to understand.</span> </code></pre>

Valid

js
const thing = foo ? bar : foobar;
js
let thing;

if (foo) {
    thing = bar;
} else if (baz === qux) {
    thing = quxx;
} else {
    thing = foobar;
}
</TabItem> </Tabs>