add babeljs

.babelrc

+{
+    "presets": [
+        "@babel/preset-env",
+        ["minify", {
+            "builtIns": false
+        }]
+    ]
+}

build/gulp/babel-js.js

+/*
+ * Copyright (c) by the ACP3 Developers.
+ * See the LICENSE file at the top-level module directory for licensing details.
+ */
+
+module.exports = (gulp, plugins) => {
+    'use strict';
+
+    const babel = require("gulp-babel");
+
+    return () => {
+        return gulp
+            .src(
+                [
+                    './ACP3/Modules/*/*/Resources/Assets/js/**/*.js',
+                    './designs/**/Assets/js/**/*.js',
+                    './installation/design/Assets/js/*.js',
+                    './installation/Installer/Modules/*/Resources/Assets/js/*.js',
+                    // Exclude all already minified files
+                    '!./ACP3/Modules/*/*/Resources/Assets/js/**/*.min.js',
+                    '!./ACP3/Modules/ACP3/Wysiwygckeditor/Resources/Assets/js/ckeditor/**/*.js',
+                    '!./designs/**/Assets/js/**/*.min.js',
+                    '!./installation/design/Assets/js/*.min.js',
+                    '!./installation/Installer/Modules/*/Resources/Assets/js/*.min.js'
+                ],
+                {base: './'}
+            )
+            .pipe(plugins.plumber())
+            .pipe(babel())
+            .pipe(plugins.rename((path) => {
+                path.basename += '.min';
+            }))
+            .pipe(gulp.dest('./'));
+    };
+};

gulpfile.js

@@ -17,6 +17,7 @@
     gulp.task('bump-version', getTask('bump-version'));
     gulp.task('scss', getTask('scss'));
     gulp.task('less', getTask('less'));
+    gulp.task('babel-js', getTask('babel-js'));
     gulp.task('watch', gulp.series('less', 'scss', getTask('watch')));
 
     gulp.task('default', gulp.series('watch'));

package.json

@@ -20,9 +20,13 @@
   "homepage": "https://www.acp3-cms.net",
   "private": true,
   "devDependencies": {
+    "@babel/core": "^7.4.3",
+    "@babel/preset-env": "^7.4.3",
     "autoprefixer": "^9.5.1",
+    "babel-preset-minify": "^0.5.0",
     "eslint": "^5.16.0",
     "gulp": "^4.0.0",
+    "gulp-babel": "^8.0.0-beta.2",
     "gulp-bump": "^3.1.3",
     "gulp-change": "^1.0.2",
     "gulp-less": "^4.0.1",