fix(deps): upgrading dependencies to address vulnerability issues (#18)

Upgrading the following dependencies:
- webpack
- webpack-cli
- loader-utils
- serialize-javascript
- replacing ugligy-webpack-plugin for terser-webpack-plugin

To address the following vulnerabilities:
- Cross-Site Scripting (XSS)
- Regular Expression Denial of Service (ReDoS) 
- Insecure serialization leading to RCE

package.json

@@ -19,13 +19,14 @@
     "babel": "^6.23.0",
     "babel-loader": "^8.1.0",
     "d3": "^5.16.0",
+    "loader-utils": "1.4.2",
     "ssf": "^0.11.0",
+    "terser-webpack-plugin": "^5.3.10",
     "ts-loader": "^7.0.5",
     "typescript": "^3.9.3",
-    "uglifyjs-webpack-plugin": "^2.2.0",
-    "webpack": "^4.43.0"
+    "webpack": "^5.94.0"
   },
   "devDependencies": {
-    "webpack-cli": "^3.3.11"
+    "webpack-cli": "^5.1.4"
   }
 }

webpack.config.js

@@ -1,6 +1,6 @@
 var path = require('path')
 
-const UglifyJSPlugin = require('uglifyjs-webpack-plugin');
+const TerserPlugin = require('terser-webpack-plugin');
 
 var webpackConfig = {
   mode: 'production',
@@ -17,13 +17,13 @@ var webpackConfig = {
     extensions: [".ts", ".js"]
   },
   plugins: [
-    new UglifyJSPlugin()
+    new TerserPlugin()
   ],
   module: {
     rules: [
       { test: /\.js$/, loader: "babel-loader" },
       { test: /\.ts$/, loader: "ts-loader" },
-      { test: /\.css$/, loader: [ 'to-string-loader', 'css-loader' ] }
+      { test: /\.css$/, use: [ {loader: 'to-string-loader'}, {loader: 'css-loader'} ] }
     ]
   },
   performance: {