Function Name Retrieval Utility

Common errors

• ReferenceError: require is not defined

  cause Attempting to use CommonJS `require()` syntax in an ES Module (ESM) context or with `get-func-name` v3.0.0+.
  fix Change your import statement to `import { getFuncName } from 'get-func-name';` and ensure your file is treated as an ES Module (e.g., using `.mjs` extension or `"type": "module"` in `package.json`).

• TypeError: (0, _getFuncName.default) is not a function OR TypeError: (0, get_func_name_1.getFuncName) is not a function

  cause Incorrectly importing the `getFuncName` function, often by using a default import (`import getFuncName from 'get-func-name';`) when it's a named export, or vice versa.
  fix Ensure you are using a named import: `import { getFuncName } from 'get-func-name';`. If you are using TypeScript, confirm your `tsconfig.json` `compilerOptions.esModuleInterop` is enabled for better module interoperability.

Warnings

• breaking Version 3.0.0 is an ES Module (ESM) only. CommonJS `require()` is no longer supported. This breaks compatibility for projects not configured for ESM.
  Fix: Migrate your import statements from `const getFuncName = require('get-func-name');` to `import { getFuncName } from 'get-func-name';` and ensure your project environment supports ESM (e.g., set `"type": "module"` in `package.json`).
• gotcha The package briefly transitioned to ESM in a v2.x release, but then reverted to CommonJS in v2.0.2. This created temporary confusion regarding its module format before the definitive ESM-only release of v3.0.0.
  Fix: Always refer to the latest major version (v3.0.0+) for ESM usage. If strict CommonJS is required, stick to versions `<3.0.0` but be aware of older security fixes.
• gotcha A security vulnerability (GHSA-4q6p-r6v2-jvc5) was addressed in v2.0.1. Using versions prior to this fix might expose your application to potential security risks.
  Fix: Upgrade to `get-func-name@2.0.1` or newer. The latest `v3.0.0` also includes this fix and is recommended.

Install

• npm install get-func-name npm
• yarn add get-func-name yarn
• pnpm add get-func-name pnpm

Imports

• getFuncName
  wrong:

  const getFuncName = require('get-func-name');

  correct:

  import { getFuncName } from 'get-func-name';

  Since v3.0.0, get-func-name is an ES Module (ESM) only. This is the correct way to import its named export. CommonJS `require` is not supported in v3+.
• getFuncName
  wrong:

  import getFuncName from 'get-func-name';

  correct:
  If `get-func-name` uses a named export for `getFuncName` (as is common for utility functions), attempting a default import will result in `undefined` or a runtime error. Use `import { getFuncName } from 'get-func-name';` instead.
• getFuncNameModule
  wrong:

  const funcName = getFuncNameModule.default(myFunction);

  correct:

  import * as getFuncNameModule from 'get-func-name';
  const funcName = getFuncNameModule.getFuncName(myFunction);

  A namespace import aggregates all named exports. For a named export like `getFuncName`, access it as a property of the namespace object (e.g., `getFuncNameModule.getFuncName`). `getFuncNameModule.default` would only be correct if the library also provided a default export for the function.

Quickstart

Demonstrates importing `getFuncName` and using it to retrieve names from various function types including named, anonymous, arrow functions, and class methods.

import { getFuncName } from 'get-func-name';

// A function with an explicit name
function myNamedFunction() {
  // ...
}

// An anonymous function assigned to a variable
const myAnonymousFunction = function() {
  // ...
};

// An arrow function
const myArrowFunction = () => {
  // ...
};

// A function nested in an IIFE, which might not have an inferable name
const nestedAnonymous = (function() {
  return function() {};
}());

console.log(`Name of myNamedFunction: '${getFuncName(myNamedFunction)}'`);
console.log(`Name of myAnonymousFunction: '${getFuncName(myAnonymousFunction)}'`);
console.log(`Name of myArrowFunction: '${getFuncName(myArrowFunction)}'`);
console.log(`Name of nestedAnonymous: '${getFuncName(nestedAnonymous)}'`);

// Example with a class method
class MyClass {
  static staticMethod() {}
  instanceMethod() {}
}

console.log(`Name of staticMethod: '${getFuncName(MyClass.staticMethod)}'`);
console.log(`Name of instanceMethod: '${getFuncName(new MyClass().instanceMethod)}'`);