Understanding esModuleInterop in tsconfig file

Understanding esModuleInterop in the tsconfig file 💻🤔

So, you've come across the esModuleInterop flag in someone's tsconfig file, and you're wondering what it does and how it relates to allowSyntheticDefaultImports. Don't worry, I'll break it down for you in simple terms! 🙌

The esModuleInterop flag is used to enable compatibility with the babel ecosystem at runtime 🏃‍♂️. It also works together with the allowSyntheticDefaultImports flag for compatibility with the TypeScript type system 🧰.

Let's first explore the allowSyntheticDefaultImports flag. According to the official documentation, it allows default imports from modules that do not have a default export 📦. This flag only affects typechecking and has no impact on the code generated or emitted.

Essentially, without the allowSyntheticDefaultImports flag, TypeScript will throw an error if you try to import a module that does not have a default export. But with this flag enabled, you can still import from such modules, even if they don't explicitly provide a default export 😮.

Now, let's link it up with esModuleInterop. The esModuleInterop flag enables the emission of __importStar and __importDefault helpers in the compiled JavaScript code. These helpers ensure compatibility with the babel ecosystem at runtime.

Additionally, enabling esModuleInterop also helps in maintaining compatibility with the TypeScript type system by enabling allowSyntheticDefaultImports. This means that you can import modules with no default export using the import module from 'module' syntax, even if the module itself doesn't provide a default export.

To recap, when esModuleInterop is set to true, it allows TypeScript to emit the necessary code for compatibility with babel and enables the use of allowSyntheticDefaultImports for importing modules without a default export 🚀.

Now, coming back to the question of using --esModuleInterop in tsconfig as opposed to it being a flag. The answer is yes! Instead of specifying --esModuleInterop as a command-line flag, you can include it in your tsconfig file under the compilerOptions section. Simply set "esModuleInterop": true within that section, just like in the example you provided.

To sum it up, esModuleInterop enables compatibility with the babel ecosystem and works in synergy with allowSyntheticDefaultImports to provide flexibility when importing modules without a default export. So go ahead, experiment with these flags in your TypeScript projects and enjoy a seamless developer experience! 😃

If you found this article helpful or have any further questions, please don't hesitate to leave a comment below! Let's level up our TypeScript skills together! 👩‍💻👨‍💻