Merge pull request #131 from koloml/bugfix/inconsistent-auto-run

Firefox: Fixed content scripts randomly loading asynchronously and not auto-running

src/content/deps/amd.ts

@@ -7,6 +7,22 @@ const originalDefine = amdLite.define;
  */
 const definedModules = new Set<string>();
 
+/**
+ * Throttle timer to make sure only one attempt at loading modules will run for a batch of loaded scripts.
+ */
+let throttledAutoRunTimer: NodeJS.Timeout | number | undefined;
+
+/**
+ * Schedule the automatic resolving of all waiting modules on the next available frame.
+ */
+function scheduleModulesAutoRun() {
+  clearTimeout(throttledAutoRunTimer);
+
+  throttledAutoRunTimer = setTimeout(() => {
+    amdLite.resolveDependencies(Object.keys(amdLite.waitingModules));
+  });
+}
+
 amdLite.define = (name, dependencies, originalCallback) => {
   // Chrome doesn't run the same content script multiple times, while Firefox does. Since each content script and their
   // chunks are intended to be run only once, we should just ignore any attempts of running the same module more than
@@ -17,20 +33,21 @@ amdLite.define = (name, dependencies, originalCallback) => {
 
   definedModules.add(name);
 
-  return originalDefine(name, dependencies, function () {
+  originalDefine(name, dependencies, function () {
     const callbackResult = originalCallback(...arguments);
 
     // Workaround for the entry script not returning anything causing AMD-Lite to send warning about modules not
     // being loaded/not existing.
     return typeof callbackResult !== 'undefined' ? callbackResult : {};
-  })
+  });
+
+  // Schedule the auto run on the next available frame. Firefox and Chromium have a lot of differences in how they
+  // decide to execute content scripts. For example, Firefox might decide to skip a frame before attempting to load
+  // different groups of them. Chromium on the other hand doesn't have that issue, but it doesn't allow us to, for
+  // example, schedule a microtask to run the modules.
+  scheduleModulesAutoRun();
 }
 
 amdLite.init({
   publicScope: window
 });
-
-// We don't have anything asynchronous, so it's safe to execute everything on the next frame.
-requestAnimationFrame(() => {
-  amdLite.resolveDependencies(Object.keys(amdLite.waitingModules))
-});