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# is-npm
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Check if your code is running as an [npm](https://docs.npmjs.com/misc/scripts) or [yarn](https://yarnpkg.com/lang/en/docs/cli/run/) script. This package provides three boolean constants that detect the package manager execution context by analyzing environment variables set by npm and yarn.
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## Package Information
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- **Package Name**: is-npm
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- **Package Type**: npm
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- **Language**: JavaScript (ES modules) with TypeScript definitions
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- **Node.js**: ^12.20.0 || ^14.13.1 || >=16.0.0
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- **Installation**: `npm install is-npm`
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## Core Imports
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```javascript
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import { isNpm, isYarn, isNpmOrYarn } from "is-npm";
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```
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For TypeScript:
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```typescript
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import { isNpm, isYarn, isNpmOrYarn } from "is-npm";
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```
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## Basic Usage
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```javascript
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import { isNpmOrYarn, isNpm, isYarn } from "is-npm";
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// Check if running under any package manager
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if (isNpmOrYarn) {
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  console.log("Running as an npm or yarn script!");
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}
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// Check specifically for npm
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if (isNpm) {
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  console.log("Running as an npm script!");
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}
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// Check specifically for yarn
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if (isYarn) {
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  console.log("Running as a yarn script!");
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}
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// Conditional logic based on execution context
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console.table({ isNpmOrYarn, isNpm, isYarn });
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```
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## Capabilities
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### Package Manager Detection
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Provides boolean constants to detect the current package manager execution context.
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```javascript { .api }
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/**
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 * Check if code is running as an npm script
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 * Detects both npm 6 (via user agent) and npm 7+ (via package.json path)
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 */
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export const isNpm: boolean;
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/**
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 * Check if code is running as a yarn script
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 * Detects yarn by checking the user agent environment variable
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 */
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export const isYarn: boolean;
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/**
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 * Check if code is running as either npm or yarn script
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 * Logical OR combination of isNpm and isYarn
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 */
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export const isNpmOrYarn: boolean;
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```
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## Detection Mechanism
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The package uses environment variables set by npm and yarn during script execution:
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- **npm detection**: Checks `process.env.npm_config_user_agent` (npm 6) and `process.env.npm_package_json` (npm 7+)
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- **yarn detection**: Checks `process.env.npm_config_user_agent` starting with "yarn"
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- **Combined detection**: Returns true if either npm or yarn is detected
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## Usage Patterns
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Common use cases for package manager detection:
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```javascript
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import { isNpmOrYarn } from "is-npm";
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// Conditional behavior in build scripts
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if (isNpmOrYarn) {
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  // Code runs only when executed via package manager
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  console.log("Running in development mode");
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} else {
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  // Code runs when executed directly with node
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  console.log("Running in production mode");
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}
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```
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```javascript
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import { isNpm, isYarn } from "is-npm";
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// Package manager specific logic
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if (isNpm) {
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  console.log("Using npm-specific configuration");
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} else if (isYarn) {
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  console.log("Using yarn-specific configuration");
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} else {
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  console.log("Running outside package manager context");
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}
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```
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## Environment Variables
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The package relies on these environment variables automatically set by package managers:
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- `npm_config_user_agent`: Contains package manager name and version (both npm and yarn)
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- `npm_package_json`: Contains path to package.json (npm 7+ only)
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These variables are automatically available when scripts are executed via `npm run` or `yarn run` commands.