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Rslint

    logical-assignment-operators

    Unreleased

    Configuration

    rslint.config.ts
    import { defineConfig, js } from '@rslint/core';

export default defineConfig([
  js.configs.recommended,
  {
    rules: {
      'logical-assignment-operators': 'error',
    },
  },
]);

    Rule Details

    This rule requires or disallows the logical assignment operators &&=, ||=, and ??=.

    By default ("always") it reports an assignment or a logical expression that duplicates its own target and can be written with a logical assignment operator instead.

    Examples of incorrect code for this rule:

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

a || (a = b);
a && (a = b);
a ?? (a = b);

    Examples of correct code for this rule:

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

a = b || c;
a || (b = c);

    enforceForIfStatements

    With { "enforceForIfStatements": true } the rule also reports an if statement whose only purpose is to assign to the value it tests.

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

    Examples of incorrect code:

    if (a) a = b;
if (!a) a = b;
if (Boolean(a)) a = b;
if (a == null) a = b;
if (a === null || a === undefined) a = b;

    Examples of correct code:

    if (a) b = c;
if (a) a = b; else a = c;
if (predicate(a)) a = b;

    never

    With "never" the rule reports every logical assignment operator and prefers the expanded form.

    { "logical-assignment-operators": ["error", "never"] }

    Examples of incorrect code:

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

    Examples of correct code:

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

    Fixes and suggestions

    The rewrite is applied automatically when it cannot change how many times a getter or a setter runs, and is offered as a suggestion otherwise.

    For a = a || b and for the never option, the target has to be a plain identifier. For a || (a = b) and for if statements, a single property access such as a.b also qualifies, as long as an if condition is a single test rather than a || chain. A bare name inside a non-strict with block may resolve to a property, so it counts as a single property access rather than a plain identifier.

    A TypeScript assertion makes the two sides count as different values, so a = a! || b and a[b!] || (a[b!] = c) are left alone.

    Original Documentation