Back to Biomejs

useThrowNewError

src/content/docs/linter/rules/use-throw-new-error.mdx

latest10.3 KB
Original Source

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

<Tabs> <TabItem label="JavaScript (and super languages)" icon="seti:javascript"> ## Summary - Rule available since: `v1.8.0` - Diagnostic Category: [`lint/style/useThrowNewError`](/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). - Sources: - Same as [`unicorn/throw-new-error`](https://github.com/sindresorhus/eslint-plugin-unicorn/blob/main/docs/rules/throw-new-error.md)

How to configure

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

Description

Require new when throwing an error.

While it's possible to instantiate Error without using the new keyword, it's better to be consistent: modern builtins require new to be instantiated.

Rule matches errors when their name ends with the word "Error" and the first character is uppercase.

Examples

Invalid

js
throw Error();
<pre class="language-text"><code class="language-text">code-block.js:1:7 <a href="https://biomejs.dev/linter/rules/use-throw-new-error">lint/style/useThrowNewError</a> <span style="color: #000; background-color: #ddd;"> FIXABLE </span> ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ <strong><span style="color: lightgreen;">ℹ</span></strong> <span style="color: lightgreen;">Use </span><span style="color: lightgreen;"><strong>new Error()</strong></span><span style="color: lightgreen;"> instead of </span><span style="color: lightgreen;"><strong>Error()</strong></span><span style="color: lightgreen;"> when throwing an error.</span> <strong><span style="color: Tomato;">&gt;</span></strong> <strong>1 │ </strong>throw Error(); <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>2 │ </strong> <strong><span style="color: lightgreen;">ℹ</span></strong> <span style="color: lightgreen;">Instantiate </span><span style="color: lightgreen;"><strong>Error</strong></span><span style="color: lightgreen;"> with </span><span style="color: lightgreen;"><strong>new</strong></span><span style="color: lightgreen;"> keyword for consistency with modern builtins.</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;">Add </span><span style="color: lightgreen;"><strong>new</strong></span><span style="color: lightgreen;"> keyword.</span> <strong> 1 │ </strong>throw<span style="opacity: 0.8;">·</span><span style="color: MediumSeaGreen;">n</span><span style="color: MediumSeaGreen;">e</span><span style="color: MediumSeaGreen;">w</span><span style="opacity: 0.8;"><span style="color: MediumSeaGreen;">·</span></span>Error(); <strong> │ </strong> <span style="color: MediumSeaGreen;">+</span><span style="color: MediumSeaGreen;">+</span><span style="color: MediumSeaGreen;">+</span><span style="color: MediumSeaGreen;">+</span> </code></pre>
js
throw TypeError('biome');
<pre class="language-text"><code class="language-text">code-block.js:1:7 <a href="https://biomejs.dev/linter/rules/use-throw-new-error">lint/style/useThrowNewError</a> <span style="color: #000; background-color: #ddd;"> FIXABLE </span> ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ <strong><span style="color: lightgreen;">ℹ</span></strong> <span style="color: lightgreen;">Use </span><span style="color: lightgreen;"><strong>new TypeError()</strong></span><span style="color: lightgreen;"> instead of </span><span style="color: lightgreen;"><strong>TypeError()</strong></span><span style="color: lightgreen;"> when throwing an error.</span> <strong><span style="color: Tomato;">&gt;</span></strong> <strong>1 │ </strong>throw TypeError('biome'); <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;">Instantiate </span><span style="color: lightgreen;"><strong>Error</strong></span><span style="color: lightgreen;"> with </span><span style="color: lightgreen;"><strong>new</strong></span><span style="color: lightgreen;"> keyword for consistency with modern builtins.</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;">Add </span><span style="color: lightgreen;"><strong>new</strong></span><span style="color: lightgreen;"> keyword.</span> <strong> 1 │ </strong>throw<span style="opacity: 0.8;">·</span><span style="color: MediumSeaGreen;">n</span><span style="color: MediumSeaGreen;">e</span><span style="color: MediumSeaGreen;">w</span><span style="opacity: 0.8;"><span style="color: MediumSeaGreen;">·</span></span>TypeError('biome'); <strong> │ </strong> <span style="color: MediumSeaGreen;">+</span><span style="color: MediumSeaGreen;">+</span><span style="color: MediumSeaGreen;">+</span><span style="color: MediumSeaGreen;">+</span> </code></pre>
js
throw lib.TypeError();
<pre class="language-text"><code class="language-text">code-block.js:1:7 <a href="https://biomejs.dev/linter/rules/use-throw-new-error">lint/style/useThrowNewError</a> <span style="color: #000; background-color: #ddd;"> FIXABLE </span> ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ <strong><span style="color: lightgreen;">ℹ</span></strong> <span style="color: lightgreen;">Use </span><span style="color: lightgreen;"><strong>new TypeError()</strong></span><span style="color: lightgreen;"> instead of </span><span style="color: lightgreen;"><strong>TypeError()</strong></span><span style="color: lightgreen;"> when throwing an error.</span> <strong><span style="color: Tomato;">&gt;</span></strong> <strong>1 │ </strong>throw lib.TypeError(); <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>2 │ </strong> <strong><span style="color: lightgreen;">ℹ</span></strong> <span style="color: lightgreen;">Instantiate </span><span style="color: lightgreen;"><strong>Error</strong></span><span style="color: lightgreen;"> with </span><span style="color: lightgreen;"><strong>new</strong></span><span style="color: lightgreen;"> keyword for consistency with modern builtins.</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;">Add </span><span style="color: lightgreen;"><strong>new</strong></span><span style="color: lightgreen;"> keyword.</span> <strong> 1 │ </strong>throw<span style="opacity: 0.8;">·</span><span style="color: MediumSeaGreen;">n</span><span style="color: MediumSeaGreen;">e</span><span style="color: MediumSeaGreen;">w</span><span style="opacity: 0.8;"><span style="color: MediumSeaGreen;">·</span></span>lib.TypeError(); <strong> │ </strong> <span style="color: MediumSeaGreen;">+</span><span style="color: MediumSeaGreen;">+</span><span style="color: MediumSeaGreen;">+</span><span style="color: MediumSeaGreen;">+</span> </code></pre>

Valid

js
throw new Error();
js
throw new TypeError('biome');
js
throw new lib.TypeError();
</TabItem> </Tabs>