If you’re using npm to manage your Node.js application dependencies, you might want to be aware of how Node.js handles environments. Node.js uses two global variables to manage your dependencies:
:npm_version defines the version of Node.js
defines the version of Node.js :npm_revision_id defines the id of the NPM version that you’re using
You can’t change your version without restarting your server! Also, NPM is very strict about maintaining the version number of your dependencies — the number of versions they support is very limited. The current version is always between v0.12 and v0.17 of the Node.js API.