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prefer-only-export

Disallow additional exports alongside a default export.

Targeted pattern scope​

This rule targets program bodies where both are true:

  • a default export exists, and
  • the file has more than one top-level statement.

What this rule reports​

This rule reports files that contain export default plus any additional top-level statement (including non-export statements).

Why this rule exists​

Some teams enforce a strict module contract: either a module exposes one default value, or it exposes named exports, but not both. Mixing both styles can make imports inconsistent across the codebase.

❌ Incorrect​

export default 1;
export const x = 1;

✅ Correct​

export default 1;
export const x = 1;
export const y = 2;

Behavior and migration notes​

This rule has no options.

Additional examples​

export default function main() {}
const helper = 1;
// ❌ reported by current implementation (second top-level statement)

export default function main() {}
// ✅ valid

ESLint flat config example​

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

export default [
 {
  plugins: { "etc-misc": etcMisc },
  rules: {
   "etc-misc/prefer-only-export": "error",
  },
 },
];

When not to use it​

Disable this rule if combining default and named exports is allowed in your modules.

Package documentation​

Rule catalog ID: R061

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.