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Blake Friedman
bfca23a25d
Summary:
Currently npx has a variety of caching strategies to avoid having to pull a version of the package from a registry. These are often unexpected to our users, who may fall behind. After looking at a variety of fancy approaches to dealing with this (the high end of which was intelligently forking npx to run `npx react-native@latest <args>`, the best possible tradeoff for time and simplicity was to warn the user when they weren't running the latest release:
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### Problem Details
On my laptop when you run `npx <package> <arguments>` this it eventually calls [libnpmexec](https://github.com/npm/cli/tree/0783cff9653928359a6c68c8fdf30b9fd02130c9/workspaces/libnpmexec), which applies this lookup [algorithm](https://github.com/npm/cli/blob/0783cff9653928359a6c68c8fdf30b9fd02130c9/workspaces/libnpmexec/lib/index.js#L39-L41) for `package@version`:
- is package available in local modules (npm root → `~/project/node_modules/<package>`)?. **Importantly it will walk all the way down to `/` looking for `node_modules/<package>`**.
- is package available in global modules (npm root -g → `/Users/blakef/.nvm/versions/node/v17.9.0/lib/node_modules`)?
- is package available in npx cache (`~/.npm/_npx`)?
- is package available in your registry? Download to the npx cache `~/.npm/_npx/<hash>/`
At this point you'll have a cached copy, which then has its bin script run with the arguments you originally provided.
### How this works against React-Native users
Users can get their development environment into a **persistent** pickle with a bunch of unintended side-effects of npx / npm exec’s caching model:
- **It matters where you run `npx react-native`**, since it’ll default to the version of react-native in a node package's folder. This works well for us in a React Native project, but not when initializing a project outside of a package folder.
- **Global and relative node_modules really matter**. If your users runs npx react-native init and they have a version of react-native installed globally, it’ll use that version.
- If the user has a `node_modules/react-native` installation anywhere in the directory hierarchy it’ll be used. For example if I run `npx react-native init Foobar` in `/home/blakef/src/example` , npx will look for versions of react-native like this before searching globals or the npx cache:
- /home/blakef/src/example/node_modules
- /home/blakef/src/node_modules
- /home/blakef/node_modules
- /home/node_modules
- /node_modules
**nvm just makes things harder** if your user switches between versions of node it can be hard to determine if they're affected by a globally installed version. Examples include having a `.nvmrc` file in the directory they run the command which transparently switches node version (and globals location).
## Changelog:
[General][Added] - Log a warning if npx react-native uses old cached version
Pull Request resolved: https://github.com/facebook/react-native/pull/37510
Test Plan: Ran this directly from the project, defining the `npm_lifecycle_event=npx` to mock directly running using `npx`.
Reviewed By: Andjeliko
Differential Revision: D46069419
Pulled By: blakef
fbshipit-source-id: 1c1af7f639c5312760a39a0828b89b7ddf2b5fda