npm stands for Node Package Manager, and is the default package manager for the JavaScript runtime environment Node.js.
To permanently set the configuration we can do this.
npm config set proxy http://proxy.company.com:8080
npm config set https-proxy http://proxy.company.com:8080
If you need to specify credentials, they can be passed in the url using the following syntax.
http://user_name:password@proxy.company.com:8080
To Redirect traffic to proxy.
npm --https-proxy=http://proxy.company.com:8080 -g install npmbox
npm --https-proxy=http://proxy.company.com:8080 -g install kafka-node
More Details.
http://wil.boayue.com/blog/2013/06/14/using-npm-behind-a-proxy/