#no-negated-condition

#Configuration

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

export default defineConfig([
  unicornPlugin.configs.recommended,
  {
    rules: {
      'unicorn/no-negated-condition': 'error',
    },
  },
]);

#Rule Details

Disallow negated conditions in if statements with an else branch and in conditional expressions. The rule reports !, !=, and !== conditions. An if without an else, or followed directly by else if, is allowed.

Examples of incorrect code for this rule:

if (!ready) {
    wait();
} else {
    start();
}

value !== expected ? fallback : result;

Examples of correct code for this rule:

if (ready) {
    start();
} else {
    wait();
}

value === expected ? result : fallback;

if (!ready) {
    wait();
}

#Fixes

The fix inverts the condition and swaps the branches. Leading comments move with their branch. Comments directly after either branch prevent automatic fixing because their association is ambiguous. Unbraced if branches gain braces when swapped.

This rule adds automatic fixes to ESLint's no-negated-condition rule. Disable the core rule when enabling this rule to avoid duplicate diagnostics.

#Options

This rule has no options. It supports automatic fixes.

#Differences from upstream

Compared with eslint-plugin-unicorn v77.0.0, automatic fixes keep code valid when removing ! would expose an object, function, or class expression at the start of a statement, an object at the start of an arrow function body, or let[...] at the start of a statement in a script. Parentheses preserve the expression, and a semicolon is added when needed to keep the preceding statement separate.

For example, !{} ? a : b becomes ({}) ? b : a, and () => !{} ? a : b becomes () => ({}) ? b : a.

#Original Documentation

• eslint-plugin-unicorn: no-negated-condition
• Source code