1.查看镜像源

npm get registry

2.临时更换

格式

npm --registry https://xxxxxxx install express

示例：临时更换淘宝源

npm --registry https://registry.npm.taobao.org install express

示例：临时重置官方源

npm --registry https://registry.npmjs.org/ install express

3..永久切换

格式

npm config set registry https://xxxxxxxx

示例：永久切换成淘宝源

npm config set registry https://registry.npm.taobao.org

示例：永久重置官方的源

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