npm install node-sass --save-dev       //安装node-sass
npm install sass-loader --save-dev         //安装依赖包sass-loader
npm install style-loader --save-dev        //安装style-loader

在build文件夹下的webpack.base.conf.js的module下 rules里面添加配置

{
    test: /\.sass$/,
    loaders: ['style', 'css', 'sass']
}