Update README.md

packages/next-upgrade/README.md

@@ -2,30 +2,42 @@
 
 Upgrade Next.js apps to newer or beta versions with one command.
 
-# Build
+```bash
+npx @next/upgrade
+```
+
+## How to use it?
+
+Simply run `npx @next/upgrade` in your project and follow the few prompts. This will let you choose between the latest canary, release candidate or stable version of Next.js.
 
-To build the package locally, go to `packages/next-upgrade` and run:
+You can also pass a specific Next.js version as an argument:
 
 ```bash
-pnpm build && pnpm link --global
+npx @next/upgrade 15.0.0-canary.148
 ```
 
-In your Next.js app, add the following to your `package.json`:
+`@next/upgrade` supports `pnpm`, `npm`, `yarn` and `bun`, and is compatible with monorepos.
 
-```json
-"dependencies": {
-  "@next/upgrade": "path/to/local/next.js/packages/next-upgrade"
-}
-```
+## Why?
 
-Finally, run:
+Updating Next.js is not just merely running `pnpm update next` or its equivalent in your package manager of choice. It also involves updating `react`, `@types/react`, `react-dom`, `@types/react-dom`, and potentially other dependencies.
+
+We noticed that trying out new or beta versions of Next.js was not as smooth as it could be, so we created this small tool that makes it easier.
+
+## Contributing
+
+To build the package locally, clone the [@vercel/next repo](https://github.com/vercel/next.js/), navigate to `packages/next-upgrade` and run:
 
 ```bash
-pnpm i
+pnpm build
 ```
 
-Now you can use the package!
+To test your local version of `@next/upgrade`, run `pnpm link --global` from the `@next/upgrade` directory and add the following to the `package.json` of your Next.js app:
 
-```bash
-npx @next/upgrade
+```json
+"dependencies": {
+  "@next/upgrade": "files:path/to/local/next.js/packages/next-upgrade"
+}
 ```
+
+Finally, run `pnpm i` and now you can use your local version of `@next/upgrade` with the standard `npx @next/upgrade` command.

packages/next-upgrade/index.ts

@@ -149,10 +149,6 @@ async function run(): Promise<void> {
     stdio: 'inherit',
   })
 
-  appPackageJson = JSON.parse(fs.readFileSync(appPackageJsonPath, 'utf8'))
-  appPackageJson.dependencies['next'] = targetVersionSpecifier
-  fs.writeFileSync(appPackageJsonPath, JSON.stringify(appPackageJson, null, 2))
-
   console.log(
     `\n${chalk.green('✔')} Your Next.js project has been upgraded successfully. ${chalk.bold('Time to ship! 🚢')}`
   )
@@ -223,7 +219,8 @@ async function getPackageManager(_packageJson: any): Promise<PackageManager> {
     bun: 'bun.lockb',
   }
 
-  function findLockFile(dir: string): PackageManager[] {
+  // Recursively looks for either a package.json with a packageManager field or a lock file
+  function resolvePackageManagerUpwards(dir: string): PackageManager[] {
     const packageJsonPath = path.join(dir, 'package.json')
     if (fs.existsSync(packageJsonPath)) {
       let detectedPackageManagers: PackageManager[] = []
@@ -251,13 +248,13 @@ async function getPackageManager(_packageJson: any): Promise<PackageManager> {
     }
     const parentDir = path.dirname(dir)
     if (parentDir !== dir) {
-      return findLockFile(parentDir)
+      return resolvePackageManagerUpwards(parentDir)
     }
     return []
   }
 
   let realPath = fs.realpathSync(process.cwd())
-  const detectedPackageManagers = findLockFile(realPath)
+  const detectedPackageManagers = resolvePackageManagerUpwards(realPath)
 
   // Exactly one package manager detected
   if (detectedPackageManagers.length === 1) {