logical-assignment-operators.md

title	layout	edit_link	rule_type
logical-assignment-operators	doc	https://github.com/eslint/eslint/edit/main/docs/src/rules/logical-assignment-operators.md	suggestion

Require or disallow assignment logical operator shorthand

Rule Details

This rule requires or disallows logical assignment operator shorthand.
On the one hand the shorthand makes it clear that the variable reference is the same. On the other hand the combined operator may be seen as "magic". This is a feature introduced in ES2021.

Options

This rule has a string and an object option. String option:

• "always" (default)
• "never"

Object option (only available if string option is set to "always"):

• "enforceForIfStatements": false(default) Do not check for equivalent if statements

• "enforceForIfStatements": true Check for equivalent if statements

always

Examples of incorrect code for this rule with the default "always" option:

::: incorrect

/*eslint logical-assignment-operators: ["error", "always"]*/

a = a || b
a = a && b
a = a ?? b

:::

Examples of correct code for this rule with the default "always" option:

::: correct

/*eslint logical-assignment-operators: ["error", "always"]*/

a = b
a ||= b
a += b

:::

never

Examples of incorrect code for this rule with the "never" option:

::: incorrect

/*eslint logical-assignment-operators: ["error", "never"]*/

a ||= b
a &&= b

:::

Examples of correct code for this rule with the "never" option:

::: correct

/*eslint logical-assignment-operators: ["error", "never"]*/

a = a || b
a = a ?? b

:::

enforceForIfStatements

This option checks for additional patterns with if statements which could be expressed with the logical assignment operator. ::: correct

/*eslint logical-assignment-operators: ["error", "always", { enforceForIfStatements: true }]*/

if (a) b = c
if (a === 0) a = b

:::

::: incorrect

/*eslint logical-assignment-operators: ["error", "always", { enforceForIfStatements: true }]*/

if (a) a = b // <=> a &&= b
if (!a) a = b // <=> a ||= b

if (a == null) a = b // <=> a ??= b
if (a === null || a === undefined) a = b // <=> a ??= b

:::

When Not To Use It

Use of logical operator assignment shorthand is a stylistic choice. Leaving this rule turned off would allow developers to choose which style is more readable on a case-by-case basis.