How to Fix "__dirname is Not Defined" in NodeJs

If you’re encountering the error __dirname is not defined in your Node.js project, it’s likely because you are using ES modules ("type": "module" in your package.json) instead of CommonJS modules. In ES modules, __dirname is not available by default. Here are some methods to fix it:

1. Manually Define __dirname

You can recreate the __dirname functionality using import.meta.url. Here’s how:

1 import { fileURLToPath } from 'url';
2 import { dirname } from 'path';
3 
4 // Create __filename and __dirname
5 const __filename = fileURLToPath(import.meta.url);
6 const __dirname = dirname(__filename);
7 
8 console.log(__dirname); // Now __dirname works

This will give you the same behavior as __dirname and __filename in CommonJS.

2. Use CommonJS (Remove "type": "module")

If you don’t need ES modules, you can remove "type": "module" from your package.json file. This way, Node.js will use CommonJS, where __dirname is natively supported.

3. Use a bundler (like Webpack or Rollup)

If you are working on a project that gets bundled for the browser (where __dirname doesn’t exist), you can configure a bundler like Webpack to polyfill it:

• In Webpack, add this to your config:

1 node: {
2   __dirname: false,
3 }

This allows you to avoid the error in your browser-based projects.

By applying one of these methods, you can resolve the __dirname issue and ensure that your project runs smoothly.