Force Yjs to Use ESM Instead of CommonJS in an MJS Project

Modern JavaScript projects increasingly adopt the MJS (ECMAScript Modules) format due to cleaner code, improved modularization, and better compatibility with modern tooling. But sometimes, libraries you’re using can conflict with this approach. Yjs, a popular real-time collaboration framework, often poses challenges as it defaults to CommonJS imports even in MJS projects. This mismatch might cause unexpected errors during development.

Error Encountered When Using Yjs CommonJS Code

A common issue developers encounter arises with Yjs’ default import method. When importing Yjs using the CommonJS method into a project fully configured for MJS, you might see errors similar to this one:

Error [ERR_REQUIRE_ESM]: require() of ES Module /path/to/project/node_modules/yjs/dist/yjs.mjs from /path/to/project/file.mjs not supported.
Instead change the require of yjs.mjs to a dynamic import() statement.

This issue occurs because Node.js’ ECMAScript Modules don’t support the use of the require() function to import ESM packages by default. This interoperability issue can disrupt the build process, complicate dependencies, and slow down your project’s pace through troubleshooting distractions.

Exploring the Yjs Distribution Folder

Navigating into the Yjs package, you will notice a distribution (“dist”) folder containing both CommonJS (*.cjs) and ESM (*.mjs) files:

• yjs.cjs (CommonJS)
• yjs.mjs (ES Module)

Given both module formats exist, a natural consideration is forcing your MJS project to directly use the ESM files provided, aligning perfectly with your modern JavaScript setup.

Analyzing your Project’s Package.json Configuration

Before proceeding, it helps to review your project’s package.json file to see the module type definition:

{
  "type": "module",
  "dependencies": {
    "yjs": "^13.5.48"
  }
}

Here, the "type": "module" setting clearly specifies that your project uses ESM by default. Thus, having incompatible CommonJS code within your dependencies naturally creates friction.

Why Choose ESM Over CommonJS?

Understanding why ESM matters helps justify taking steps to align Yjs imports appropriately. ESM offers several clear advantages over the older CommonJS standard:

• Support for Modern JavaScript Features: ESM adheres closely to JavaScript’s evolution, providing native support for features such as dynamic imports, asynchronous programming, and easier debugging.
• Improved Tree-Shaking: ESM modules support efficient tree-shaking, allowing bundlers like Webpack or Vite to remove unnecessary components, significantly reducing your overall package size.
• Better Compatibility: Modern JavaScript projects and frameworks, including React, Vue, and Svelte, heavily favor the use of ESM, ensuring smoother interoperability with third-party libraries and tools.

On the flip side, continuing to use CommonJS generates several downsides:

• Limited interoperability: Mixing ESM and CommonJS modules complicates configurations with bundlers, leading to errors and complexity.
• Reduced performance: Lack of proper tree-shaking inflates the build size and increases loading time, slowing application responsiveness in production environments.

Clearly, aligning your project fully with ESM principles offers considerable benefits in maintainability, scalability, and overall performance.

Forcing Yjs to Utilize ESM in Your MJS Project

Thankfully, ensuring Yjs uses ESM correctly is straightforward:

1. Explicitly reference the ESM file from Yjs within your import statement. Instead of importing the default way:

   import * as Y from 'yjs';
   

   Force Node.js to pick the ESM module directly by specifying:

   import * as Y from 'yjs/dist/yjs.mjs';
   

2. If you utilize bundlers such as Webpack or Vite, ensure your bundle and module resolution configurations properly prioritize ESM files by updating your bundler configuration as required (generally these tools handle ESM effectively by default).
3. Confirm your installed Yjs version supports ESM fully by validating your package manager’s installed version:

   npm ls yjs
   

   Upgrade if necessary:

   npm update yjs
   

After applying these changes, re-run your build and start scripts. You’ll find your previous import errors resolved, creating a smoother development experience.

Testing the ESM Implementation

Make sure to test rigorously after making the module switch:

• Run your standard tests to confirm existing functionalities are working as expected.
• Create specific small-scale tests to verify Yjs methods and functionalities remain available, ensuring reliability.
• If any new errors surface, visiting communities like Stack Overflow, or Yjs’ GitHub repository will help efficiently resolve remaining conflicts.

Best Practices for Leveraging ECMAScript Modules

Once Yjs successfully employs ESM, consider these recommendations for optimizing module use across your entire JavaScript project:

• Logical Module Groupings: Organize modules logically by functionality rather than size or complexity. Clearly defined modules improve readability, maintainability, and teamwork efficiency.
• Avoid Deeply Nested Imports: Structure your project neatly to prevent deep nested imports. This practice fosters clear and maintainable codebases while simplifying module replacement or refactoring.
• Leverage Dynamic Imports Effectively: Dynamic imports allow conditional loading, improving performance significantly. Use dynamic imports strategically to load heavy components or third-party scripts on demand, enhancing your application’s performance.

By intentionally incorporating these best practices, you enhance code readability, maintainability, and significantly improve your project’s efficiency and scalability.

Switching Yjs explicitly to ESM represents a proactive step towards modernizing your JavaScript ecosystem. Doing so significantly improves interoperability, tightens module structure, and aligns with contemporary development practices. Ultimately, this migration translates directly to better-performing and more maintainable applications.

Have you encountered issues or solved other interesting compatibility challenges with ESM-based projects or libraries? Share your experience and solutions in the comments below!