How to Import a Module with ".js" in its Name Without Triggering a TypeError?

When working with JavaScript modules importing files with the a .js extension can sometimes cause issues particularly when using the modern module syntax. This guide will explain the common pitfalls and how to import these modules correctly.

We are going to discuss these topics in brief:

Understanding the Issue

In JavaScript, when we import a module using the ES6 module syntax the filename extension (like .js) should not be included in the import statement. Including the extension can lead to errors especially if the module is not structured correctly or does not adhere to ECMAScript module standards.

Common Error: TypeError

The TypeError typically arises when the JavaScript runtime encounters an unexpected type or when there is a problem with the module loading or execution. Importing a module incorrectly such as the including the .js extension can trigger this error.

Steps to import a module with ".js" in its name without triggering a TypeError

To correctly import a module with a .js extension without the triggering a TypeError follow these steps:

Step 1: Correct Module Export

Ensure that the module we are importing is correctly exported using the export keyword in its .js file.

// myModule.js
export function myFunction() {
    // Module function code
}

Step 2: Specifying the type in package.json

{
  "type": "module"
}

Step 3: Import without ".js" Extension

In your main JavaScript file import the module without including the .js extension:

// main.js
import { myFunction } from './myModule.js'; // Correct
// Usage of myFunction
myFunction();

Step 4: Verify Module Path

The Double-check the path to the module file relative to the current JavaScript file. Ensure that the path is correct and that the module file exists in the specified the location.

Step 5: Module Loading Order

Make sure that the module loading order is correct if we are using the multiple modules. JavaScript modules are loaded asynchronously so dependencies should be resolved the correctly.

Step 6: Check Browser Support

If we are working with the browser-based JavaScript ensure that the browser supports ECMAScript modules (<script type="module">) and that the type="module" attribute is correctly set in the HTML file.

Conclusion

By following these steps, we can avoid triggering TypeError when importing modules with the .js extensions in JavaScript. Remember to adhere to the ECMAScript module standards and use correct import syntax to the ensure smooth module loading and execution in the JavaScript applications.