https://github.com/zetlen/npm-is
Detect the package manager client running the current script.
https://github.com/zetlen/npm-is
Last synced: about 1 month ago
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Detect the package manager client running the current script.
- Host: GitHub
- URL: https://github.com/zetlen/npm-is
- Owner: zetlen
- Created: 2020-05-05T22:35:20.000Z (about 6 years ago)
- Default Branch: master
- Last Pushed: 2020-05-06T14:43:54.000Z (about 6 years ago)
- Last Synced: 2025-02-15T23:47:30.481Z (over 1 year ago)
- Language: JavaScript
- Size: 11.7 KB
- Stars: 0
- Watchers: 0
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
Awesome Lists containing this project
README
Detect the package manager client running the current script.
Detects NPM and yarn, as well as any hard executable path.
Use this when your project requires a specific package manager to work
correctly, such as a monorepo using Yarn workspaces.
It can help your package scripts exit early if they're being invoked outside of
the required package manager.
## Recommended Usage
In a monorepo, or any repo with `private: true`, it's safe to catch things as
early as possible.
Add a `preinstall` script to prevent the wrong package manager from even
beginning to install dependencies.
Use `npx` to dynamically install `npm-is` before any other
modules are installed.
```diff
{
"name": "my-yarn-only-monorepo",
"version": "1.0.0",
"private": true,
"workspaces": [
"packages/*"
]
"scripts": {
+ "preinstall": "npx npm-is yarn"
}
}
```
Now, this happens when you try to `npm install`.
```sh
$ npm install
> my-yarn-only-monorepo@1.0.0 preinstall /Users/me/repo
> npx npm-is yarn
/Users/me/repo/node_modules/npm-is/npm-is.js:54
throw new WrongPackageManagerError(allowed, invoked);
^
Error: This project can only be used with the "yarn" package manager, but it was
invoked by "npm", which is not supported.
```
## Install
**Don't install this as a dependency if you're going to use it in the**
**[recommended way described above](#Recommended_usage).**
**Instead, run it with `npx` so that it works before dependencies are installed!**
But if you insist:
with npm: `npm install --save-dev npm-is`
with yarn: `yarn add --dev npm-is`
## Advanced Usage
### CLI
With no arguments, `npm-is` prints the current package manager.
So, running it outside a package manager with no arguments, it will print
nothing.
Running it inside an NPM script with NPM should print `npm` to the command line.
With arguments, `npm-is` will take each of its arguments to be
allowed package managers.
If the `preinstall` script is `"npm-is yarn npm"`, then install
will only succeed if the package manager in use is Yarn or NPM.
Only `npm` and `yarn` are currently supported as shorthand.
If you're using a custom package manager, you must know its exec path (that is,
the value of the environment variable `$npm_execpath` when it is running
lifecycle scripts) and pass that as an argument.
If the `preinstall` script is `"npm-is /path/to/pnpm`, then
install will only succeed if `$npm_execpath` is exactly `/path/to/pnpm`.
### Node API
```js
const npmIs = require("npm-is");
// returns true if Yarn
npmIs("yarn");
// returns true if Yarn or NPM
npmIs(["yarn", "npm"]);
// returns true if Yarn, NPM, or custom executable
npmIs(["yarn", "npm", "/some/custom/one"]);
// Throws instead of returning false
npmIs.assert("yarn");
npmIs.assert(["yarn", "npm"]);
npmIs.assert(["yarn", "npm", "/some/custom/one"]);
// Returns "npm" if NPM, "yarn" if Yarn,
// empty string if no package manager,
// or full execPath if anything else
npmIs.detect();
```