A Webpack loader for running arbitrary shell scripts when loading files.
npm install --save-dev shell-loaderAdd shell-loader your Webpack configuration object, setting options.script to the shell script you want to run on each file. Example;
module: {rules: [{test: /.*\.css$/,use: ['css-loader',{loader: 'shell-loader',options: {script: 'postcss --use autoprefixer'}}]}]}