noYodaExpression

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/noYodaExpression`](/reference/diagnostics#diagnostic-category) - This rule isn't recommended, so you need to enable it. - This rule has a [**safe**](/linter/#safe-fixes) fix. - The default severity of this rule is [**information**](/reference/diagnostics#information). - Sources: - Same as [`yoda`](https://eslint.org/docs/latest/rules/yoda)

How to configure

json

{
	"linter": {
		"rules": {
			"style": {
				"noYodaExpression": "error"
			}
		}
	}
}

Description

Disallow the use of yoda expressions.

A Yoda expression is a programming style where, given a binary operation, the "static" part of the binary operation is placed on the left-hand side. This rule forbids the use of Yoda expressions and enforces the placing of the "static" part of the binary operations on the right-hand side.

Exceptions

Range expressions like 0 < value && value < 1 or value <= 0 || 1 < value are allowed.

Examples

Invalid

if ("red" == value) {}

<pre class="language-text"><code class="language-text">code-block.js:1:5 <a href="https://biomejs.dev/linter/rules/no-yoda-expression">lint/style/noYodaExpression</a> FIXABLE ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ ℹ Avoid the use of yoda expressions. > 1 │ if ("red" == value) {} │ ^^^^^^^^^^^^^^ 2 │ ℹ Yoda expressions can be confusing to some people, invert the expression operands for better readability. ℹ Safe fix: Flip the operators of the expression. 1 │ - if·("red"·==·value)·{} 1 │ + if·(value·==·"red")·{} 2 2 │ </code></pre>

if (true === value) {}

<pre class="language-text"><code class="language-text">code-block.js:1:5 <a href="https://biomejs.dev/linter/rules/no-yoda-expression">lint/style/noYodaExpression</a> FIXABLE ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ ℹ Avoid the use of yoda expressions. > 1 │ if (true === value) {} │ ^^^^^^^^^^^^^^ 2 │ ℹ Yoda expressions can be confusing to some people, invert the expression operands for better readability. ℹ Safe fix: Flip the operators of the expression. 1 │ - if·(true·===·value)·{} 1 │ + if·(value·===·true)·{} 2 2 │ </code></pre>

if (5 != value) {}

<pre class="language-text"><code class="language-text">code-block.js:1:5 <a href="https://biomejs.dev/linter/rules/no-yoda-expression">lint/style/noYodaExpression</a> FIXABLE ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ ℹ Avoid the use of yoda expressions. > 1 │ if (5 != value) {} │ ^^^^^^^^^^ 2 │ ℹ Yoda expressions can be confusing to some people, invert the expression operands for better readability. ℹ Safe fix: Flip the operators of the expression. 1 │ - if·(5·!=·value)·{} 1 │ + if·(value·!=·5)·{} 2 2 │ </code></pre>

Valid

if (value === "red") {}

if (value === value) {}

if (value != 5) {}

if (0 < value && value < 1) {}

Resources

Wikipedia definition

</TabItem> </Tabs>