换源
更换npm源地址
npm config set registry https://registry.npm.taobao.org
检查npm原地址
npm config get registry
出现错误
npm info retry will retry, error on last attempt: Error: CERT_UNTRUSTED
解决方法
npm config set strict-ssl false
cnpm代替npm
npm install -g cnpm --registry=https://registry.npm.taobao.org