npm config set proxy http://proxy.company.com:8080
npm config set https-proxy http://proxy.company.com:8080
 
# or
export npm_config_proxy http://proxy.company.com:8080
export npm_config_https_proxy http://proxy.company.com:8080
 
# or
npm --https-proxy=http://proxy.company.com:8080 -g install karma

npm config set strict-ssl false
npm config set registry "http://registry.npmjs.org/"
npm --proxy http://username:password@cacheaddress.com.br:80 install packagename