extracts inlined source map and offers it to webpack

source map loader for webpack

Extracts SourceMaps for source files that as added as sourceMappingURL comment.

Documentation: Using loaders

module.exports = {
  module: {
    preLoaders: [
        test: /\.js$/,
        loader: "source-map-loader"

This extracts all SourceMaps from all files. That's not so performance-wise so you may only want to apply the loader to relevant files.