Use webpack-merge.

Move html export config to own file.
Delete unnecessary config options.
Use cheap source maps.

Signed-off-by: David Mehren <dmehren1@gmail.com>

webpack.dev.js

@@ -1,41 +1,14 @@
-var baseConfig = require('./webpack.common')
-const MiniCssExtractPlugin = require('mini-css-extract-plugin')
-var path = require('path')
+const common = require('./webpack.common.js')
+const htmlexport = require('./webpack.htmlexport')
+const merge = require('webpack-merge')
 
-module.exports = [Object.assign({}, baseConfig, {
-  plugins: baseConfig.plugins.concat([
-    new MiniCssExtractPlugin({
-      filename: '[name].css',
-      chunkFilename: '[id].css'
-    })
-
-  ]),
-  devtool: 'source-map'
-}), {
-  devtool: 'source-map',
-  entry: {
-    htmlExport: path.join(__dirname, 'public/js/htmlExport.js')
-  },
-  module: {
-    rules: [{
-      test: /\.css$/,
-      use: ['style-loader', 'css-loader']
-    }, {
-      test: /\.scss$/,
-      use: ['style-loader', 'sass-loader']
-    }, {
-      test: /\.less$/,
-      use: ['style-loader', 'less-loader']
-    }]
-  },
-  output: {
-    path: path.join(__dirname, 'public/build'),
-    publicPath: '/build/',
-    filename: '[name].js'
-  },
-  plugins: [
-    new MiniCssExtractPlugin({
-      filename: 'html.min.css'
-    })
-  ]
-}]
+module.exports = [
+  // merge common config
+  merge(common, {
+    mode: 'development',
+    devtool: 'cheap-module-eval-source-map'
+  }),
+  merge(htmlexport, {
+    mode: 'development',
+    devtool: 'cheap-module-eval-source-map'
+  })]