Upgrade dev dependencies

package.json

@@ -5,17 +5,17 @@
   "main": "./dist/float-sidebar.min.js",
   "module": "./dist/float-sidebar.js",
   "devDependencies": {
-    "babel-core": "^6.26.0",
-    "babel-loader": "^7.1.3",
-    "babel-plugin-transform-object-assign": "^6.22.0",
+    "babel-core": "^6.26.3",
+    "babel-loader": "7",
+    "babel-plugin-transform-object-assign": "6",
     "babel-plugin-transform-object-rest-spread": "^6.26.0",
     "babel-preset-es2015": "6.24.1",
-    "uglifyjs-webpack-plugin": "^1.1.6",
-    "webpack": "4.2.0",
-    "webpack-cli": "2.0.9"
+    "terser-webpack-plugin": "^3.0.0",
+    "webpack": "4.42.1",
+    "webpack-cli": "3.3.11"
   },
   "scripts": {
-    "test": "echo \"Error: no test specified\" && exit 1"
+    "build": "webpack"
   },
   "repository": {
     "type": "git",

webpack.config.js

@@ -2,7 +2,7 @@ const webpack = require('webpack');
 const path    = require('path');
 const pkg     = require('./package.json');
 
-const UglifyJsPlugin = require('uglifyjs-webpack-plugin');
+const TerserPlugin = require('terser-webpack-plugin');
 
 const banner = [
   `${pkg.name} - ${pkg.description}`,
@@ -40,13 +40,16 @@ module.exports = {
   },
 
   optimization: {
-    minimize: false
+    minimize: true,
+    minimizer: [
+      new TerserPlugin({
+        include: /\.min\.js$/,
+        extractComments: false
+      })
+    ],
   },
 
   plugins: [
-    new UglifyJsPlugin({
-      include: /\.min\.js$/,
-    }),
     new webpack.BannerPlugin(banner)
   ]
 }