is-npm-not-yarn Detect if code is running as an npm script but not a yarn script. Note: Use with >= yarn@1 requires >= is-npm-not-yarn@2. Install Use JS var isNpmNotYarn = require('is-npm-not-yarn')console.log(isNpmNotYarn) // true or false CLI is-npm-not-yarn exit code of 0 if is npm and not yarn, else 1