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@kreisler/dirname-for-module

A lightweight utility that provides __dirname functionality for ES modules. When using ECMAScript modules (ESM) with import/export syntax, the global __dirname variable is not available. This package provides a drop-in replacement.

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The Problem

In CommonJS modules, __dirname is automatically available: 
// CommonJS (works)
const path = require('path');
const configPath = path.join(__dirname, 'config.json');
But in ES modules, __dirname is undefined: 
// ES Module (doesn't work!)
import path from 'path';
const configPath = path.join(__dirname, 'config.json'); // ❌ ReferenceError: __dirname is not defined

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The Solution

This package exports a pre-calculated __dirname that works in ES modules: 
import { __dirname } from '@kreisler/dirname-for-module';
import path from 'path';

const configPath = path.join(__dirname, 'config.json'); // ✅ Works!

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Installation

npm install @kreisler/dirname-for-module

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Usage

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Basic Usage

import { __dirname } from '@kreisler/dirname-for-module';

console.log(__dirname);
// Output: /home/user/my-project (your current directory)

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With Path Operations

import { __dirname } from '@kreisler/dirname-for-module';
import { join } from 'path';

// Resolve paths relative to current directory
const configPath = join(__dirname, 'config', 'app.json');
const publicDir = join(__dirname, 'public');
const dataFile = join(__dirname, '..', 'data', 'users.json');

console.log(configPath); // /home/user/my-project/config/app.json

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Reading Files

import { __dirname } from '@kreisler/dirname-for-module';
import { readFileSync } from 'fs';
import { join } from 'path';

// Read a config file relative to current directory
const configPath = join(__dirname, 'config.json');
const config = JSON.parse(readFileSync(configPath, 'utf-8'));

console.log(config);

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Dynamic Imports

import { __dirname } from '@kreisler/dirname-for-module';
import { join } from 'path';

// Load modules relative to current directory
const pluginPath = join(__dirname, 'plugins', 'my-plugin.js');
const plugin = await import(pluginPath);

plugin.initialize();

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Express.js Static Files

import { __dirname } from '@kreisler/dirname-for-module';
import express from 'express';
import { join } from 'path';

const app = express();

// Serve static files from public directory
app.use(express.static(join(__dirname, 'public')));

// Set views directory for templates
app.set('views', join(__dirname, 'views'));

app.listen(3000);

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TypeScript Configuration

import { __dirname } from '@kreisler/dirname-for-module';
import { readFileSync } from 'fs';
import { join } from 'path';

// Load TypeScript config
const tsconfigPath = join(__dirname, 'tsconfig.json');
const tsconfig = JSON.parse(readFileSync(tsconfigPath, 'utf-8'));

console.log(tsconfig.compilerOptions);

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How It Works

Under the hood, the package uses Node.js built-in utilities to calculate the directory name: 
import { fileURLToPath } from 'url';
import { dirname } from 'path';

// Convert import.meta.url to file path
const __filename = fileURLToPath(import.meta.url);

// Extract directory name
export const __dirname = dirname(__filename);
The package also handles different module resolution strategies:
  • Regular node_modules installations
  • PNPM’s unique content-addressable storage
  • Scoped packages (e.g., @organization/package)

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Alternative: Manual Implementation

If you prefer not to add a dependency, you can implement this yourself in any ES module file: 
import { fileURLToPath } from 'url';
import { dirname } from 'path';

const __filename = fileURLToPath(import.meta.url);
const __dirname = dirname(__filename);

// Now use __dirname as normal
console.log(__dirname);
The advantage of using this package is that it handles edge cases with different package managers (especially PNPM) and module resolution strategies.

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Common Use Cases

import { __dirname } from '@kreisler/dirname-for-module';
import { readFileSync } from 'fs';
import { join } from 'path';

const config = JSON.parse(
  readFileSync(join(__dirname, 'config.json'), 'utf-8')
);

import { __dirname } from '@kreisler/dirname-for-module';
import { writeFileSync, mkdirSync } from 'fs';
import { join } from 'path';

// Create output directory
const outputDir = join(__dirname, 'output');
mkdirSync(outputDir, { recursive: true });

// Write file
const filePath = join(outputDir, 'result.json');
writeFileSync(filePath, JSON.stringify(data));

import { __dirname } from '@kreisler/dirname-for-module';
import express from 'express';
import { join } from 'path';

const app = express();

app.use('/static', express.static(join(__dirname, 'public')));
app.use('/uploads', express.static(join(__dirname, 'uploads')));

import { __dirname } from '@kreisler/dirname-for-module';
import { join } from 'path';

const templatePath = join(__dirname, 'templates', 'email.html');
const template = await readFile(templatePath, 'utf-8');

import { __dirname } from '@kreisler/dirname-for-module';
import { join } from 'path';

const migrationDir = join(__dirname, 'migrations');
const seedDir = join(__dirname, 'seeds');

// Use with your migration tool

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TypeScript Support

The package includes TypeScript definitions and works seamlessly with TypeScript projects: 
import { __dirname } from '@kreisler/dirname-for-module';

// __dirname is typed as string
const dir: string = __dirname;

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tsconfig.json

Make sure your tsconfig.json is configured for ES modules: 
{
  "compilerOptions": {
    "module": "ESNext",
    "moduleResolution": "node",
    "target": "ES2020"
  }
}

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package.json

Ensure your package is configured as an ES module: 
{
  "type": "module",
  "main": "./dist/index.mjs",
  "types": "./dist/index.d.mts"
}

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Comparison with Alternatives

Pros:
  • Simple one-line import
  • Handles edge cases (PNPM, scoped packages)
  • Zero configuration
  • Minimal overhead
Cons:
  • Adds a small dependency
import { __dirname } from '@kreisler/dirname-for-module';

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Package Manager Compatibility

This package is tested and works with:
1

npm

Standard Node.js package manager
npm install @kreisler/dirname-for-module
2

pnpm

Fast, disk space efficient package manager
pnpm add @kreisler/dirname-for-module
The package includes special handling for PNPM’s unique module resolution strategy.
3

Yarn

Popular npm alternative
yarn add @kreisler/dirname-for-module

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Troubleshooting

“Error [ERR_REQUIRE_ESM]: require() of ES Module not supported”This error means you’re trying to use require() with an ES module. Solutions:
  1. Add "type": "module" to your package.json
  2. Use .mjs file extension
  3. Use import instead of require
“ReferenceError: __dirname is not defined”Make sure you’ve imported the package:
import { __dirname } from '@kreisler/dirname-for-module';
NOT:
// ❌ This won't work
console.log(__dirname); // undefined

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Migration Guide

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From CommonJS to ES Modules

Before (CommonJS): 
// index.js
const path = require('path');
const configPath = path.join(__dirname, 'config.json');
After (ES Module): 
// index.mjs or index.js with "type": "module"
import { __dirname } from '@kreisler/dirname-for-module';
import path from 'path';

const configPath = path.join(__dirname, 'config.json');

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API Reference

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Exports

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__dirname
string
The absolute path of the directory containing the module
Example: 
import { __dirname } from '@kreisler/dirname-for-module';

console.log(__dirname);
// Output: /Users/username/projects/my-app

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Support

If you find this package helpful, consider:

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License

MIT © Kreisler

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