nrm是一个npm源管理工具，可以快速的切换npm源
安装
npm install -g nrm
使用
1. 列出可用的源
nrm ls
* npm ----- https://registry.npmjs.org/
cnpm ---- http://r.cnpmjs.org/
taobao -- https://registry.npm.taobao.org/
nj ------ https://registry.nodejitsu.com/
rednpm -- http://registry.mirror.cqupt.edu.cn
skimdb -- https://skimdb.npmjs.com/registry
2. 切换源
nrm use taobao
Registry has been set to: https://registry.npm.taobao.org/
