If you're working on a TypeScript project and suddenly ran into the "ReferenceError: exports is not defined" issue, don't worry, you're not alone in facing this. This error typically indicates a problem with the module system and how TypeScript is handling module imports and exports.
The first thing to understand is that TypeScript uses ES modules by default, which differ from how traditional Node.js modules work. ES modules use the `import` and `export` statements, whereas Node.js CommonJS modules use `require()` and `module.exports`. The `exports is not defined` error is common when there's a mix-up between these module systems.
To fix this issue in a pure TypeScript project, there are a few steps you can take:
1. Check your tsconfig.json file: Make sure your `tsconfig.json` file is correctly configured to use ES modules. Look for the `"module"` field and set it to `"ESNext"` or `"ES6"`. This tells TypeScript to treat your code as ES modules.
2. Update your import/export statements: Review all your import and export statements in your TypeScript files. Ensure you're using the ES module syntax. For exports, use `export` instead of `module.exports`. For imports, use `import` instead of `require()`.
3. Verify your Node.js version: If you're running your TypeScript project in a Node.js environment, check the Node.js version you're using. Make sure it supports ES module syntax. Node.js 12 and later versions have better support for ES modules.
4. Use type: module in package.json: If you're using Node.js 12 or later, ensure your `package.json` file includes `"type": "module"`. This signals to Node.js that your project uses ES modules.
5. Resolving circular dependencies: Another common cause of the `exports is not defined` error is circular dependencies between your modules. Make sure you refactor your code to remove any circular dependencies.
6. Webpack or other bundlers: If you're bundling your TypeScript code using Webpack or another bundler, check the configuration settings related to modules. Ensure the bundler is set up to handle ES modules correctly.
7. Check for typos and file paths: Sometimes, simple errors like typos in file paths or module names can trigger the `exports is not defined` error. Double-check your code for any such mistakes.
By following these steps, you should be able to resolve the `ReferenceError: exports is not defined` issue in your pure TypeScript project. Remember to pay attention to the differences between ES modules and CommonJS modules, as mismatches in module systems often lead to this error. Keep your TypeScript code clean, modular, and in line with ES module syntax for smooth error-free development. Happy coding!