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'

解决:

npm config set registry http://registry.npmjs.org/

so that npm requests for http url instead of https.

and then try the same npm install command