The npm install command will install the devDependencies along other dependencies when run inside a package directory, in a development environment (the default).
Use npm install --only=prod (or --only=production) to install only dependencies, and not devDependencies,regardless of the value of the NODE_ENV environment variable.
https://stackoverflow.com/questions/9268259/how-do-you-prevent-install-of-devdependencies- npm-modules-for-node-js-package