DEV: Remove vendored babel and update config for plugins/themes (#17832)

The new plugin list is based on the ones currently used in our ember-cli pipeline, and are based on our official browser support policy.

This commit includes an update to the raw-handlebars compiler to remove the 'very hacky but lets us use ES6' code. It's  served us well for the last 6 years, but the babel config changes broke it (`const` -> `let`). This commit takes the opportunity to refactor it to take a similar approach to PrettyText, by leaning on `mini-loader.js`.

app/assets/javascripts/discourse/package.json

@@ -17,6 +17,7 @@
   },
   "dependencies": {
     "@babel/core": "^7.18.5",
+    "@babel/standalone": "^7.18.12",
     "@discourse/itsatrap": "^2.0.10",
     "@ember/jquery": "^2.0.0",
     "@ember/optional-features": "^2.0.0",

app/assets/javascripts/yarn.lock

@@ -957,6 +957,11 @@
   dependencies:
     regenerator-runtime "^0.13.4"
 
+"@babel/standalone@^7.18.12":
+  version "7.18.12"
+  resolved "https://registry.yarnpkg.com/@babel/standalone/-/standalone-7.18.12.tgz#4c0abdf1b5213394e73a0ba5500dcc287194a20d"
+  integrity sha512-wDh3K5IUJiSMAY0MLYBFoCaj2RCZwvDz5BHn2uHat9KOsGWEVDFgFQFIOO+81Js2phFKNppLC45iOCsZVfJniw==
+
 "@babel/template@^7.16.7", "@babel/template@^7.18.6":
   version "7.18.6"
   resolved "https://registry.yarnpkg.com/@babel/template/-/template-7.18.6.tgz#1283f4993e00b929d6e2d3c72fdc9168a2977a31"

lib/discourse_js_processor.rb

@@ -4,6 +4,25 @@ require 'mini_racer'
 
 class DiscourseJsProcessor
 
+  DISCOURSE_COMMON_BABEL_PLUGINS = [
+    'proposal-optional-chaining',
+    ['proposal-decorators', { legacy: true } ],
+    'transform-template-literals',
+    'proposal-class-properties',
+    'proposal-class-static-block',
+    'proposal-private-property-in-object',
+    'proposal-private-methods',
+    'proposal-numeric-separator',
+    'proposal-logical-assignment-operators',
+    'proposal-nullish-coalescing-operator',
+    'proposal-json-strings',
+    'proposal-optional-catch-binding',
+    'transform-parameters',
+    'proposal-async-generator-functions',
+    'proposal-object-rest-spread',
+    'proposal-export-namespace-from',
+  ]
+
   def self.plugin_transpile_paths
     @@plugin_transpile_paths ||= Set.new
   end
@@ -94,9 +113,10 @@ class DiscourseJsProcessor
     def self.create_new_context
       # timeout any eval that takes longer than 15 seconds
       ctx = MiniRacer::Context.new(timeout: 15000, ensure_gc_after_idle: 2000)
-      ctx.eval("var self = this; #{File.read("#{Rails.root}/vendor/assets/javascripts/babel.js")}")
+      ctx.eval("#{File.read("#{Rails.root}/app/assets/javascripts/node_modules/@babel/standalone/babel.js")}")
       ctx.eval(File.read(Ember::Source.bundled_path_for('ember-template-compiler.js')))
       ctx.eval("module = {}; exports = {};")
+      ctx.eval("const DISCOURSE_COMMON_BABEL_PLUGINS = #{DISCOURSE_COMMON_BABEL_PLUGINS.to_json};")
       ctx.attach("rails.logger.info", proc { |err| Rails.logger.info(err.to_s) })
       ctx.attach("rails.logger.error", proc { |err| Rails.logger.error(err.to_s) })
       ctx.eval <<JS
@@ -156,9 +176,34 @@ JS
 
       if opts[:module_name] && !@skip_module
         filename = opts[:filename] || 'unknown'
-        "Babel.transform(#{js_source}, { moduleId: '#{opts[:module_name]}', filename: '#{filename}', ast: false, presets: ['es2015'], plugins: [['transform-modules-amd', {noInterop: true}], 'proposal-object-rest-spread', 'proposal-optional-chaining', ['proposal-decorators', {legacy: true} ], 'proposal-class-properties', exports.WidgetHbsCompiler] }).code"
+        <<~JS
+          Babel.transform(
+            #{js_source},
+            {
+              moduleId: '#{opts[:module_name]}',
+              filename: '#{filename}',
+              ast: false,
+              plugins: [
+                exports.WidgetHbsCompiler,
+                ['transform-modules-amd', {noInterop: true}],
+                ...DISCOURSE_COMMON_BABEL_PLUGINS
+              ]
+            }
+          ).code
+        JS
       else
-        "Babel.transform(#{js_source}, { ast: false, plugins: ['proposal-json-strings', 'proposal-nullish-coalescing-operator', 'proposal-logical-assignment-operators', 'proposal-numeric-separator', 'proposal-optional-catch-binding', 'transform-dotall-regex', 'proposal-unicode-property-regex', 'transform-named-capturing-groups-regex', 'proposal-object-rest-spread', 'proposal-optional-chaining', 'transform-arrow-functions', 'transform-block-scoped-functions', 'transform-block-scoping', 'transform-computed-properties', 'transform-destructuring', 'transform-duplicate-keys', 'transform-for-of', 'transform-function-name', 'transform-literals', 'transform-object-super', 'transform-parameters', 'transform-shorthand-properties', 'transform-spread', 'transform-sticky-regex', 'transform-template-literals', 'transform-typeof-symbol', 'transform-unicode-regex', ['proposal-decorators', {legacy: true}], 'proposal-class-properties', exports.WidgetHbsCompiler] }).code"
+        <<~JS
+          Babel.transform(
+            #{js_source},
+            {
+              ast: false,
+              plugins: [
+                exports.WidgetHbsCompiler,
+                ...DISCOURSE_COMMON_BABEL_PLUGINS
+              ]
+            }
+          ).code
+        JS
       end
     end
 

lib/freedom_patches/raw_handlebars.rb

@@ -10,20 +10,20 @@ class Barber::Precompiler
 
   def precompiler
     if !@precompiler
-
+      loader = File.read("#{Rails.root}/app/assets/javascripts/mini-loader.js")
       source = File.read("#{Rails.root}/app/assets/javascripts/discourse-common/addon/lib/raw-handlebars.js")
-      transpiler = DiscourseJsProcessor::Transpiler.new(skip_module: true)
-      transpiled = transpiler.perform(source)
 
-      # very hacky but lets us use ES6. I'm ashamed of this code -RW
-      transpiled = transpiled[transpiled.index('var RawHandlebars = ')...transpiled.index('export ')]
+      transpiled = DiscourseJsProcessor.transpile(source, "#{Rails.root}/app/assets/javascripts/", "discourse-common/lib/raw-handlebars")
 
       @precompiler = StringIO.new <<~JS
-        var __RawHandlebars;
-        (function() {
-          #{transpiled};
-          __RawHandlebars = RawHandlebars;
-        })();
+        let __RawHandlebars;
+
+        (function(){
+          #{loader}
+          define("handlebars", ["exports"], function(exports){ exports.default = Handlebars; })
+          #{transpiled}
+          __RawHandlebars = require("discourse-common/lib/raw-handlebars").default;
+        })()
 
         Barber = {
           precompile: function(string) {
@@ -31,6 +31,7 @@ class Barber::Precompiler
           }
         };
       JS
+
     end
 
     @precompiler

spec/models/theme_field_spec.rb

@@ -197,7 +197,7 @@ HTML
     expect(theme.javascript_cache.content).to include('addRawTemplate("discovery"')
     expect(theme.javascript_cache.content).to include("define(\"discourse/theme-#{theme.id}/controllers/discovery\"")
     expect(theme.javascript_cache.content).to include("define(\"discourse/theme-#{theme.id}/controllers/discovery-2\"")
-    expect(theme.javascript_cache.content).to include("var settings =")
+    expect(theme.javascript_cache.content).to include("const settings =")
   end
 
   def create_upload_theme_field!(name)

spec/models/theme_spec.rb

@@ -248,22 +248,8 @@ HTML
       )
       expect(javascript_cache.content).to include("name: \"theme-field-#{field.id}-mobile-html-script-1\",")
       expect(javascript_cache.content).to include("after: \"inject-objects\",")
-      expect(javascript_cache.content).to include("(0, _pluginApi.withPluginApi)(\"0.1\", function (api) {")
-      expect(javascript_cache.content).to include("var x = 1;")
-    end
-
-    it "replaces const writes with _readOnlyError function call" do
-      html = <<HTML
-        <script type='text/discourse-plugin' version='0.1'>
-          const x = 1;
-          x = 2;
-        </script>
-HTML
-
-      baked, javascript_cache = transpile(html)
-      expect(baked).to include(javascript_cache.url)
-      expect(javascript_cache.content).to include('var x = 1;')
-      expect(javascript_cache.content).to include('2, _readOnlyError("x");')
+      expect(javascript_cache.content).to include("(0, _pluginApi.withPluginApi)(\"0.1\", api =>")
+      expect(javascript_cache.content).to include("const x = 1;")
     end
   end
 
@@ -369,9 +355,9 @@ HTML
       )
       expect(theme_field.javascript_cache.content).to include("name: \"theme-field-#{theme_field.id}-common-html-script-1\",")
       expect(theme_field.javascript_cache.content).to include("after: \"inject-objects\",")
-      expect(theme_field.javascript_cache.content).to include("(0, _pluginApi.withPluginApi)(\"1.0\", function (api)")
+      expect(theme_field.javascript_cache.content).to include("(0, _pluginApi.withPluginApi)(\"1.0\", api =>")
       expect(theme_field.javascript_cache.content).to include("alert(settings.name)")
-      expect(theme_field.javascript_cache.content).to include("var a = function a() {}")
+      expect(theme_field.javascript_cache.content).to include("let a = () => {}")
 
       setting = theme.settings.find { |s| s.name == :name }
       setting.value = 'bill'