Use webpack to deliver underscore (and use newest version)

app/assets/javascripts/application.js

@@ -23,5 +23,4 @@
 //= require ace/ace
 //= require ace/ext-language_tools
 //= require jquery-ui.min
-//= require underscore.min
 //= require_tree .

app/javascript/packs/application.js

@@ -12,6 +12,8 @@ import 'jquery'
 import 'bootstrap/dist/js/bootstrap.bundle.min';
 import 'chosen-js/chosen.jquery';
 import 'jstree';
+import 'underscore';
+window._ = _; // Publish underscore's `_` in global namespace
 
 // CSS
 import 'chosen-js/chosen.css';

config/webpack/environment.js

@@ -15,6 +15,7 @@ environment.plugins.prepend('Provide', new webpack.ProvidePlugin({
         jquery: 'jquery',
         'window.Tether': "tether",
         Popper: ['popper.js', 'default'], // for Bootstrap 4
+        _: 'underscore',
     })
 );
 
@@ -22,7 +23,8 @@ const envConfig = module.exports = environment;
 const aliasConfig = module.exports = {
     resolve: {
         alias: {
-            jquery: 'jquery/src/jquery'
+            jquery: 'jquery/src/jquery',
+            underscore: 'underscore/underscore',
         }
     }
 };

package.json

@@ -7,6 +7,7 @@
     "jquery": "^3.3.1",
     "jstree": "^3.3.5",
     "popper.js": "^1.14.4",
+    "underscore": "^1.9.1",
     "webpack-merge": "^4.1.4"
   },
   "devDependencies": {

yarn.lock

@@ -6475,6 +6475,11 @@ uglifyjs-webpack-plugin@^1.2.7:
     webpack-sources "^1.1.0"
     worker-farm "^1.5.2"
 
+underscore@^1.9.1:
+  version "1.9.1"
+  resolved "https://registry.yarnpkg.com/underscore/-/underscore-1.9.1.tgz#06dce34a0e68a7babc29b365b8e74b8925203961"
+  integrity sha512-5/4etnCkd9c8gwgowi5/om/mYO5ajCaOgdzj/oW+0eQV9WxKBDZw5+ycmKmeaTXjInS/W0BzpGLo2xR2aBwZdg==
+
 union-value@^1.0.0:
   version "1.0.0"
   resolved "https://registry.yarnpkg.com/union-value/-/union-value-1.0.0.tgz#5c71c34cb5bad5dcebe3ea0cd08207ba5aa1aea4"