referenceerror module is not defined in es module scope

Referenceerror: module is not defined in es module scope

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When working with ES Modules, you may encounter the “ReferenceError: module is not defined in ES module scope” error.

This article explores the causes of this error and offers solutions to resolve it.

What is Referenceerror: module is not defined in es module scope?

The error message “ReferenceError: module is not defined in ES module scope” occurs in JavaScript when you try to use the module keyword in a context where it is not recognized or supported.

The module keyword is used in ECMAScript (ES) modules to define and export functionality that can be imported by other modules.

It allows you to encapsulate code and expose specific parts of it to be used elsewhere.

However, this error typically arises in one of the following situations:

  • Browser Support: Some older browsers do not support native ES modules.
  • Node.js CommonJS Modules: The “module” keyword is not recognized in the CommonJS module system used by Node.js.

Example of Referenceerror

Here’s an example of a complete program that can generate the “ReferenceError: module is not defined in ES module scope” error:

// main.js
module.exports = {
  greeting: "Hello, world!"
};


// index.html
<script type="module">
  import { greeting } from './main.js';
  console.log(greeting);
</script>

In this example, we have two files: main.js and index.html.

The main.js file is written using CommonJS module syntax (Node.js style), where we use the module.exports syntax to export an object with a greeting property set to the string “Hello, world!”.

The index.html file is an HTML file with a <script> tag set to type=”module”, indicating that the script should be treated as an ES module.

Inside the script, we use the import statement to import the greeting variable from the main.js module.
Finally, we log the greeting variable to the console.

If you try to run this code directly in a browser without using a module bundler or a transpiler, you will likely encounter the “ReferenceError: module is not defined in ES module scope” error.

This is because the browser does not recognize the module keyword, as it is not supported in all browsers.

Solutions – Referenceerror: module is not defined in es module scope

To fix the “ module is not defined in es module scope” error in your code, you can consider the following solutions:

Solution 1. Use a Module Bundler

Install webpack using npm or yarn: npm install webpack –save-dev or yarn add webpack –dev.

Create a webpack configuration file named webpack.config.js with the following content:

const path = require('path');

module.exports = {
  entry: './main.js',
  output: {
    filename: 'bundle.js',
    path: path.resolve(__dirname, 'dist'),
  },
};

Modify your code:

// main.js
export const greeting = "Hello, world!";

Build the bundle by running npx webpack or yarn webpack. This will create a bundle.js file in the dist folder.

Create an HTML file, index.html, with the following content:

<script src="dist/bundle.js" type="module"></script>

Open index.html in a browser, and the error should be resolved.

Solution 2. Use a Transpiler (Babel)

Install Babel and the necessary plugins using npm or yarn:

npm install @babel/core @babel/cli @babel/preset-env --save-dev

Create a .babelrc configuration file with the following content:

{
  "presets": ["@babel/preset-env"]
}

Modify your code:

// main.js
export const greeting = "Hello, world!";

Transpile the code by running npx babel main.js –out-file bundle.js or yarn babel main.js –out-file bundle.js.
Create an HTML file, index.html, with the following content:

<script src="bundle.js" type="module"></script>

Open index.html in a browser, and the error should be resolved.

These solutions utilize a module bundler (webpack) and a transpiler (Babel) to handle the conversion and bundling of ES modules for browser compatibility.

Anyway, here are other fixed errors you can refer to when you might encounter them.

Conclusion

In conclusion, the “ReferenceError: module is not defined in ES module scope” error occurs when you try to use the module keyword in a context where it is not recognized or supported.

To resolve this error, you have a few options:

  • Use a Module Bundler
  • Transpile Your Code

We hope this guide has assisted you in resolving the error effectively.

Until next time! 😊

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