npm安装spm报错:network If you are behind a proxy, plea

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'

npm config set registry http://registry.npmjs.org/[/code]
 so that npm requests for 
http
 url instead of 
https
.
and then try the same 
npm install
 command