#no-multi-assign

#Configuration

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

export default defineConfig([
  js.configs.recommended,
  {
    rules: {
      'no-multi-assign': 'error',
    },
  },
]);

#Rule Details

This rule disallows chained assignment expressions within a single statement, such as a = b = c. Chained assignments are often a sign of a typo (foo = bar == 0 was meant) and they hide whether each name is being declared or merely reassigned, which can lead to surprising scope and const-vs-let mistakes.

Examples of incorrect code for this rule:

var a = b = c = 5;

const foo = bar = "baz";

let a =
  b =
    c;

class Foo {
  a = b = 10;
}

a = b = "quux";

Examples of correct code for this rule:

var a = 5;
var b = 5;
var c = 5;

const foo = "baz";
const bar = "baz";

let a = 5;
let b = 5;
let c = 5;

class Foo {
  a = 10;
  b = 10;
}

a = "quux";
b = "quux";

#Options

This rule has an object option:

• "ignoreNonDeclaration": When set to true, allows chained assignments that do not introduce new declarations (i.e. plain AssignmentExpressions). Defaults to false.

Examples of correct code for this rule with { "ignoreNonDeclaration": true }:

{ "no-multi-assign": ["error", { "ignoreNonDeclaration": true }] }

let a;
let b;
a = b = "baz";

const x = {};
const y = {};
x.one = y.one = 1;

Examples of incorrect code for this rule with { "ignoreNonDeclaration": true }:

{ "no-multi-assign": ["error", { "ignoreNonDeclaration": true }] }

let a = b = "baz";

const foo = bar = 1;

class Foo {
  a = b = 10;
}

#Original Documentation

• ESLint no-multi-assign