Hello !
I would like to install bower as global package (field "Global npm packages to install" in the "Global Tool Configuration").
Error :
..............
npm ERR! network getaddrinfo ENOTFOUND registry.npmjs.org registry.npmjs.org:443
npm ERR! network This is most likely not a problem with npm itself
npm ERR! network and is related to network connectivity.
npm ERR! network In most cases you are behind a proxy or have bad network settings.
npm ERR! network
npm ERR! network If you are behind a proxy, please make sure that the
npm ERR! network 'proxy' config is set properly. See: 'npm help config'
............

I tried to create a "NPM config file" in "Config File Management", with this content :
proxy=http://<proxy>:<port>/
https-proxy=http://<proxy><port>/
and using it in my job --> still error

The only way to have bower install globally behind the proxy is to use this "NPM config file" and to use the shell command "npm install -g bower"

It's not blocking but uncomfortable because Jenkins will try to install bower at each job use.

Thanks