When working with Node.js, ES6 Modules can bring a lot of modern features and syntax improvements to your JavaScript code. However, migrating from the traditional CommonJS modules to ES6 modules in Node.js can sometimes lead to the "Error: Cannot find module '...' and 'ERR_REQUIRE_ESM'". This issue occurs because Node.js treats files with the ".js" extension as CommonJS modules by default. To successfully use ES6 modules in Node.js 12 and above, you need to follow a few steps.
### Step 1: Set "type" Field in package.json
To inform Node.js that your project is using ES6 modules, you first need to add a "type" field in your `package.json` file. Open the `package.json` and add the following line:
"type": "module"### Step 2: Update File Extensions
Since Node.js considers files with the ".js" extension as CommonJS modules, you should rename your files to have the ".mjs" extension for them to be recognized as ES6 modules. For example, if you have a file named `index.js`, change it to `index.mjs`.
### Step 3: Importing Modules
When importing modules in ES6 syntax, use `import` and `export` statements. For example, if you have a file named `utils.mjs` with the following content:
export function myFunction() {
return 'Hello, ES6 Modules!';
}You can import and use this function in another module like this:
import { myFunction } from './utils.mjs';
console.log(myFunction());### Step 4: Running the Application
To run your Node.js application that uses ES6 modules, you need to use the `--experimental-modules` flag followed by the entry file of your application. For example, if your main file is `app.mjs`, you can run your application using the following command:
node --experimental-modules app.mjs### Additional Tips:
- Remember that ES6 modules do not support `require()` and `module.exports`.
- Ensure that you update your code to comply with ES6 module syntax.
- Be mindful of the differences in scope and behavior between ES6 modules and CommonJS modules.
By following these steps and best practices, you can successfully use ES6 modules in Node.js 12 and above without encountering the "Error: ERR_REQUIRE_ESM". Embracing ES6 modules can lead to cleaner, more maintainable code that takes advantage of the latest JavaScript features. Happy coding with ES6 modules in Node.js!