add NodeNext summary to the README

README.md

@@ -12,50 +12,117 @@ $ npm install --save-dev fastify-tsconfig
 
 Create your own `tsconfig.json` in the projects' root folder and extend it from `fastify-tsconfig`, overriding or adding the desired settings. By default, no `outDir` is set (because of [this issue](https://github.com/Microsoft/TypeScript/issues/29172)), so be sure to add one.
 
+### Configuration module and moduleResolution
+
+This configuration sets `"module"` and `"moduleResolution"` to [`NodeNext`](https://www.typescriptlang.org/docs/handbook/esm-node.html). This means that TypeScript will read the nearest `package.json` file in the scope and search for the `"type"` field or the absence of it.
+
+If `type` is not set or is `"type": "commonjs"` the emitted code will be CommonJS, with `.js` extension. Moreover, `tsc` will complain if ESM-only properties/features are used in source files. If you want to emit `.mjs` files, use the `.mts` extension.
+On the other hand, if `"type": "module"` is set, the sources will be compiled to the ESM with the `.js` extension. In this case, if you want to emit `.cjs` files, use the `.cts` extension for the source file.
+
+The "following the Node.js rules" goes also for the `package.json` `exports` field. If `type` is set, regardless of the value, TypeScript will check the `exports` field to know where the compiled code and the types are located. If the `type` field is not set, it will check for the `main` and `types` fields.
+
+#### CommonJS example
+`package.json`
+```jsonc
+{
+  "name": "my-package",
+  "type": "commonjs",
+  "main": "dist/index.js", // this is for older Node.js versions
+  "types": "dist/index.d.ts", // this is optional and can be omitted
+  "exports": {
+    "import": "./dist/index.js",
+    "require": "./dist/index.js",
+    "types": "./dist/index.d.ts" // this is optional and can be omitted
+ }
+}
+```
+`tsconfig.json`
+```jsonc
+{
+ "extends": "fastify-tsconfig",
+ "compilerOptions": {
+    "outDir": "dist",
+    "sourceMap": true
+  },
+  "include": [
+    "src/**/*.ts"
+  ]
+}
+```
+#### ESM example
+`package.json`
+```jsonc
+{
+  "name": "my-package",
+  "type": "module",
+  "main": "dist/index.js", // this is for older Node.js versions
+  "types": "dist/index.d.ts", // this is optional and can be omitted
+  "exports": {
+    "import": "./dist/index.js",
+    "require": "./dist/index.js",
+    "types": "./dist/index.d.ts" // this is optional and can be omitted
+ }
+}
+```
+`tsconfig.json`
+```jsonc
+{
+ "extends": "fastify-tsconfig",
+ "compilerOptions": {
+    "outDir": "dist",
+    "sourceMap": true
+  },
+  "include": [
+    "src/**/*.ts"
+  ]
+}
+```
+### Extending this configuration
+
 Depending on the type of the project, you should add the following settings.
 
-### Application
+#### Application
 `tsconfig.json`
 ```json
 {
  "extends": "fastify-tsconfig",
  "compilerOptions": {
- "outDir": "dist",
- "sourceMap": true
+    "outDir": "dist",
+    "sourceMap": true
  },
  "include": [
- "src/**/*.ts"
+    "src/**/*.ts"
  ]
 }
 ```
-### Package
+#### NPM Package
 `tsconfig.json`
 
 ```json
 {
  "extends": "fastify-tsconfig",
  "compilerOptions": {
- "outDir": "dist",
- "declaration": true
+    "outDir": "dist",
+    "declaration": true
  },
  "include": [
- "src/**/*.ts"
+    "src/**/*.ts"
  ]
 }
 ```
-### Monorepo Package
+#### Monorepo Package
 `tsconfig.json`
 
 ```json
 {
  "extends": "fastify-tsconfig",
  "compilerOptions": {
- "outDir": "dist",
- "declarationMap": true,
- "composite": true
+    "outDir": "dist",
+    "declarationMap": true,
+    "composite": true
  },
  "include": [
- "src/**/*.ts"
+    "src/**/*.ts"
  ]
 }
 ```

package.json

@@ -1,6 +1,6 @@
 {
   "name": "fastify-tsconfig",
-  "version": "2.0.0",
+  "version": "1.0.1",
   "description": "Shared TypeScript configuration",
   "license": "MIT",
   "repository": {
@@ -14,7 +14,7 @@
   },
   "main": "tsconfig.json",
   "engines": {
-    "node": ">=16.13.2"
+    "node": ">=18.0.0"
   },
   "files": [
     "tsconfig.json"