vue踩坑-Error: Can't resolve 'sass-loader' in 'E:\Element-UI-master\src\components'

报错的原因
不能解析sass-loader

Failed to compile.
 
./src/components/Map.vue
Module not found: Error: Can't resolve 'sass-loader' in 'E:\Element-UI-master\src\components'
 @ ./src/components/Map.vue 4:2-346
 @ ./src/router/index.js
 @ ./src/main.js
 @ multi ./node_modules/_webpack-dev-server@2.11.5@webpack-dev-server/client?http://localhost:8081 webpack/hot/dev-server ./src/main.js

解决办法：

1. cnpm install sass-loader -D
2. cnpm install node-sass -D