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uppercase-iife

Disallow unreadable immediately invoked arrow function expressions.

Targeted pattern scope​

This rule targets immediately invoked arrow function expressions (IIFEs).

What this rule reports​

This rule reports IIFEs whose arrow function body is an unnecessary parenthesized expression.

Why this rule exists​

Extra parentheses in IIFE arrow bodies reduce readability and add noise.

❌ Incorrect​

(() => doWork())();

✅ Correct​

(() => doWork())();

Behavior and migration notes​

This rule forwards options and behavior to unicorn/no-unreadable-iife.

Additional examples​

const value = (() => compute())();
// ❌ reported by forwarded unicorn rule

const valueFixed = (() => compute())();
// ✅ valid

ESLint flat config example​

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

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

When not to use it​

Disable this rule if your team deliberately keeps this parenthesized IIFE style for historical consistency.

Package documentation​

Rule catalog ID: R078

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.