Use core-js as polyfill to really support older browsers.

.babelrc

@@ -1,13 +1,6 @@
 {
   "presets": [["@babel/preset-env", {
-      "targets": {
-        "chrome": 45,
-        "firefox": 42,
-        "safari": 9,
-        "opera": 32,
-        "edge": 12,
-        "ios": 9
-      },
+      "corejs": 3,
       "loose": false,
       "useBuiltIns": "entry"
       }]

.browserslistrc

@@ -0,0 +1,2 @@
+>1%
+not ie > 9

package.json

@@ -14,8 +14,9 @@
   },
   "dependencies": {
     "bootstrap": "^3",
-    "eonasdan-bootstrap-datetimepicker": "^4.17.47",
     "chart.js": "^2",
+    "core-js": "^3",
+    "eonasdan-bootstrap-datetimepicker": "^4.17.47",
     "jquery": "^3.3.1",
     "jquery-ui": "^1.11.2",
     "moment": "^2.8.2",
@@ -38,6 +39,7 @@
     "optimize-css-assets-webpack-plugin": "^5.0.1",
     "rimraf": "^2.6.2",
     "style-loader": "^0.23.1",
+    "terser-webpack-plugin": "^1.3.0",
     "webpack": "^4.27.0",
     "webpack-cli": "^3.1.2"
   }

resources/assets/js/vendor.js

@@ -1,3 +1,4 @@
+require('core-js/stable');
 window.$ = window.jQuery = require('jquery');
 require('imports-loader?define=>false!jquery-ui');
 require('bootstrap');

webpack.config.js

@@ -2,6 +2,7 @@ const path = require('path');
 const webpack = require('webpack');
 const MiniCssExtractPlugin = require('mini-css-extract-plugin');
 const OptimizeCSSAssetsPlugin = require('optimize-css-assets-webpack-plugin');
+const TerserPlugin = require('terser-webpack-plugin');
 const nodeEnv = (process.env.NODE_ENV || 'development').trim();
 
 // eslint-disable-next-line
@@ -43,7 +44,7 @@ module.exports = {
     publicPath: '',
   },
   optimization: {
-    minimizer: __DEV__ ? [] : [new OptimizeCSSAssetsPlugin({})],
+    minimizer: __DEV__ ? [] : [new OptimizeCSSAssetsPlugin({}), new TerserPlugin()],
   },
   module: {
     rules: [