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no-negated-conditions

Disallow negated conditions.

Targeted pattern scope​

This rule reports selected negation patterns in conditions:

  • if (!value)
  • if (value !== other)
  • top-level logical combinations that include those negations (&& / ||)

The selector is intentionally focused and does not rewrite all possible boolean equivalences.

What this rule reports​

This rule reports selected negated patterns in conditions and top-level logical expressions, including !foo and foo !== bar forms.

Why this rule exists​

Negated conditions can increase cognitive load, especially in compound boolean expressions. Positive predicates are usually easier to scan and reason about.

❌ Incorrect​

if (!x && y) {
}
if (x !== 1 && y) {
}
const value = !x || y;

✅ Correct​

if (x && y) {
}
if (x === 1 && y) {
}
const value = x && y;

Behavior and migration notes​

This rule reports only and does not provide an autofix.

Migrations typically involve flipping comparisons (!== → ===) and restructuring condition branches for positive checks.

Options​

This rule has no options.

Additional examples​

if (!isReady || hasError) {
 return;
}
// ❌ reported

if (isReady && hasNoError) {
 start();
}
// ✅ valid when predicates are already positive.

ESLint flat config example​

import etcMisc from "eslint-plugin-etc-misc";

export default [
 {
  plugins: { "etc-misc": etcMisc },
  rules: {
   "etc-misc/no-negated-conditions": "error",
  },
 },
];

When not to use it​

Disable this rule if your codebase intentionally allows negated condition forms.

Package documentation​

Rule catalog ID: R033

Further reading​

Adoption resources​

  • Start at warning level in CI, then move to error after cleanup.
  • Use focused codemods/autofix batches per package or directory.