Update Sprockets

Gemfile

@@ -107,7 +107,7 @@ gem "clockwork"
 gem "mini_racer", "~> 0.8.0"
 gem "nokogiri", ">= 1.10.4"
 gem "image_processing"
-gem "sprockets", "~> 4.0.0"
+gem "sprockets", "~> 4.2.0"
 
 group :production do
   # Reduce the noise of logs and include custom fields to it for easier access

Gemfile.lock

@@ -553,9 +553,9 @@ GEM
     snaky_hash (2.0.0)
       hashie
       version_gem (~> 1.1)
-    sprockets (4.0.3)
+    sprockets (4.2.0)
       concurrent-ruby (~> 1.0)
-      rack (> 1, < 3)
+      rack (>= 2.2.4, < 4)
     sprockets-rails (3.4.2)
       actionpack (>= 5.2)
       activesupport (>= 5.2)
@@ -700,7 +700,7 @@ DEPENDENCIES
   simple_form
   simplecov
   skylight
-  sprockets (~> 4.0.0)
+  sprockets (~> 4.2.0)
   standard (~> 1.28)
   stimulus-rails
   strong_migrations (= 1.4.4)

config/importmap.rb

@@ -7,7 +7,7 @@
 pin "startup", to: "startup.js", preload: true
 pin "@hotwired/turbo-rails", to: "turbo.min.js", preload: true
 pin "@hotwired/stimulus", to: "stimulus.min.js", preload: true
-pin "@hotwired/stimulus-loading", to: "stimulus-loading.js", preload: true
+pin "@hotwired/stimulus-loading", to: "stimulusloading.js", preload: true
 pin_all_from "app/javascript/controllers", under: "controllers"
 pin_all_from "app/javascript/utils", under: "utils"
 pin "bootstrap", to: "https://ga.jspm.io/npm:[email protected]/dist/js/bootstrap.js"

vendor/javascript/stimulusloading.js

@@ -0,0 +1,85 @@
+// FIXME: es-module-shim won't shim the dynamic import without this explicit import
+import "@hotwired/stimulus"
+
+const controllerAttribute = "data-controller"
+const registeredControllers = {}
+
+// Eager load all controllers registered beneath the `under` path in the import map to the passed application instance.
+export function eagerLoadControllersFrom(under, application) {
+  const paths = Object.keys(parseImportmapJson()).filter(path => path.match(new RegExp(`^${under}/.*_controller$`)))
+  paths.forEach(path => registerControllerFromPath(path, under, application))
+}
+
+function parseImportmapJson() {
+  return JSON.parse(document.querySelector("script[type=importmap]").text).imports
+}
+
+function registerControllerFromPath(path, under, application) {
+  const name = path
+    .replace(new RegExp(`^${under}/`), "")
+    .replace("_controller", "")
+    .replace(/\//g, "--")
+    .replace(/_/g, "-")
+
+  if (!(name in registeredControllers)) {
+    import(path)
+      .then(module => registerController(name, module, application))
+      .catch(error => console.error(`Failed to register controller: ${name} (${path})`, error))
+  }
+}
+
+
+// Lazy load controllers registered beneath the `under` path in the import map to the passed application instance.
+export function lazyLoadControllersFrom(under, application, element = document) {
+  lazyLoadExistingControllers(under, application, element)
+  lazyLoadNewControllers(under, application, element)
+}
+
+function lazyLoadExistingControllers(under, application, element) {
+  queryControllerNamesWithin(element).forEach(controllerName => loadController(controllerName, under, application))
+}
+
+function lazyLoadNewControllers(under, application, element) {
+  new MutationObserver((mutationsList) => {
+    for (const { attributeName, target, type } of mutationsList) {
+      switch (type) {
+        case "attributes": {
+          if (attributeName == controllerAttribute && target.getAttribute(controllerAttribute)) {
+            extractControllerNamesFrom(target).forEach(controllerName => loadController(controllerName, under, application))
+          }
+        }
+
+        case "childList": {
+          lazyLoadExistingControllers(under, application, target)
+        }
+      }
+    }
+  }).observe(element, { attributeFilter: [controllerAttribute], subtree: true, childList: true })
+}
+
+function queryControllerNamesWithin(element) {
+  return Array.from(element.querySelectorAll(`[${controllerAttribute}]`)).map(extractControllerNamesFrom).flat()
+}
+
+function extractControllerNamesFrom(element) {
+  return element.getAttribute(controllerAttribute).split(/\s+/).filter(content => content.length)
+}
+
+function loadController(name, under, application) {
+  if (!(name in registeredControllers)) {
+    import(controllerFilename(name, under))
+      .then(module => registerController(name, module, application))
+      .catch(error => console.error(`Failed to autoload controller: ${name}`, error))
+  }
+}
+
+function controllerFilename(name, under) {
+  return `${under}/${name.replace(/--/g, "/").replace(/-/g, "_")}_controller`
+}
+
+function registerController(name, module, application) {
+  if (!(name in registeredControllers)) {
+    application.register(name, module.default)
+    registeredControllers[name] = true
+  }
+}