Add Tell Node To Treat JS Files As ESM as a JavaScript TIL

javascript/tell-node-to-treat-js-files-as-esm.md

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+# Tell Node To Treat JS Files As ESM
+
+By default, Node will treat all `.js` files as CommonJS. That means you'll need
+to use the CommonJS export and require syntax to share code between files. If
+you'd instead like to opt-in to ESM (ECMAScript Modules), you'll need to update
+your `package.json`.
+
+Add the following line:
+
+```json
+"type": "module",
+```
+
+This will tell node that instead of CJS, it should treat all `.js` files as
+ESM. This means that ESM-based `export` and `import` syntax will work.
+
+This also means you don't need to be defining your files with the `.mjs`
+extension.
+
+For more extensive reading on this, see:
+
+- [ECMAScript Modules in Node.js](https://www.typescriptlang.org/docs/handbook/esm-node.html)
+- [Getting Started with (and Surviving) Node.js ESM](https://formidable.com/blog/2021/node-esm-and-exports/)
+- [`.mts` is a cool file extension (TypeScript ES modules)](https://mtsknn.fi/blog/mts-file-extension/)