NPM Registry Proxy 配置，解决访问国外 NPM 源超时、中断等问题。
Porxy
$ npm config set proxy http://server:port
$ npm config set https-proxy http://server:port
$ cat ~/.npmrc
registry=https://mirrors.cloud.tencent.com/npm/
home=https://mirrors.cloud.tencent.com/npm/
nrm
快速切换npm源，安装
sudo npm install -g nrm
查看源：
$ nrm ls
npm ---------- https://registry.npmjs.org/
yarn --------- https://registry.yarnpkg.com/
tencent ------ https://mirrors.cloud.tencent.com/npm/
cnpm --------- https://r.cnpmjs.org/
taobao ------- https://registry.nlark.com/
npmMirror ---- https://skimdb.npmjs.com/registry/
测速：
nrm test
切换：
nrm use tencent
其他：
nrm add <registry> <url> [home]
nrm del <registry>