1Firstly, sassLoader and postcss are not valid webpack config attributes https://webpack.js.org/configuration
2
3The way you would typically go about it is to add the .scss file to your entry
4
5 entry: {
6 app: './src/app.js',
7 styles: './pathtoyourstyles/style.scss'
8 },
9and then add the appropriate loaders.
10
11loaders: [
12 {
13 test: /\.scss$/,
14 loaders: ["style-loader", "css-loader", "sass-loader"]
15 }
16]