npm, yarn查看源和换源：
npm config get registry // 查看npm当前镜像源
npm config set registry https://registry.npmjs.org
yarn config get registry // 查看yarn当前镜像源
yarn config set registry https://registry.yarnpkg.com
镜像源地址部分如下：
npm --- https://registry.npmjs.org/
npm --- https://registry.npm.taobao.org/
yarn --- https://registry.yarnpkg.com/
yarn --- https://registry.npm.taobao.org/
cnpm --- https://r.cnpmjs.org/
taobao --- https://registry.npm.taobao.org/
nj --- https://registry.nodejitsu.com/
rednpm --- https://registry.mirror.cqupt.edu.cn/
npmMirror --- https://skimdb.npmjs.com/registry/
deunpm --- http://registry.enpmjs.org/
