fix(explorer): debounce dirty notifications and ignore vendorChunk

angular.json

@@ -22,6 +22,7 @@
             "main": "src/main.ts",
             "polyfills": "src/polyfills.ts",
             "tsConfig": "tsconfig.app.json",
+            "vendorChunk": false,
             "aot": true,
             "assets": ["src/favicon.ico", "src/assets"],
             "styles": [
@@ -45,7 +46,6 @@
               "extractCss": true,
               "namedChunks": false,
               "extractLicenses": true,
-              "vendorChunk": false,
               "buildOptimizer": true,
               "budgets": [
                 {
@@ -133,6 +133,7 @@
             "main": "projects/shell-chrome/src/main.ts",
             "polyfills": "projects/shell-chrome/src/polyfills.ts",
             "tsConfig": "projects/shell-chrome/tsconfig.app.json",
+            "vendorChunk": false,
             "aot": true,
             "assets": [
               "projects/shell-chrome/src/favicon.ico",
@@ -158,7 +159,6 @@
               "extractCss": true,
               "namedChunks": false,
               "extractLicenses": true,
-              "vendorChunk": false,
               "buildOptimizer": true,
               "budgets": [
                 {

projects/ng-devtools-backend/src/lib/change-detection-tracker.ts

@@ -1,20 +1,14 @@
 import { buildDirectiveForest, ComponentTreeNode } from './component-tree';
 import { runOutsideAngular, patchTemplate } from './utils';
+import { Subject } from 'rxjs';
 
-let hookInitialized = false;
+export const onChangeDetection$ = new Subject();
 
-export const onChangeDetection = (callback: () => void): void => {
-  if (hookInitialized) {
-    return;
-  }
-  const forest = buildDirectiveForest();
-  listenAndNotifyOnUpdates(forest, callback);
-  hookInitialized = true;
-};
+const forest = buildDirectiveForest();
 
 // We patch the component tView template function reference
 // to detect when the change detection has completed and notify the client.
-const listenAndNotifyOnUpdates = (roots: ComponentTreeNode[], callback: () => void): void => {
+const listenAndNotifyOnUpdates = (roots: ComponentTreeNode[]): void => {
   roots.forEach((root) => {
     const { component } = root;
     if (!component) {
@@ -23,8 +17,10 @@ const listenAndNotifyOnUpdates = (roots: ComponentTreeNode[], callback: () => vo
     }
     patchTemplate(component.instance, () => {
       runOutsideAngular(() => {
-        setTimeout(callback, 0);
+        setTimeout(() => onChangeDetection$.next(), 0);
       });
     });
   });
 };
+
+listenAndNotifyOnUpdates(forest);

projects/ng-devtools-backend/src/lib/client-event-subscribers.ts

@@ -9,7 +9,7 @@ import {
   ProfilerFrame,
   ComponentExplorerViewQuery,
 } from 'protocol';
-import { onChangeDetection } from './change-detection-tracker';
+import { onChangeDetection$ } from './change-detection-tracker';
 import { ComponentTreeNode, getLatestComponentState, queryDirectiveForest, updateState } from './component-tree';
 import { start as startProfiling, stop as stopProfiling } from './observer';
 import { serializeDirectiveState } from './state-serializer/state-serializer';
@@ -18,6 +18,7 @@ import { setConsoleReference } from './selected-component';
 import { unHighlight } from './highlighter';
 import { getAngularVersion, appIsAngularInDevMode, appIsSupportedAngularVersion } from './angular-check';
 import { observeDOM, getDirectiveId, getDirectiveForest, indexDirectiveForest } from './component-tree-identifiers';
+import { debounceTime } from 'rxjs/operators';
 
 export const subscribeToClientEvents = (messageBus: MessageBus<Events>): void => {
   messageBus.on('shutdown', shutdownCallback(messageBus));
@@ -37,7 +38,11 @@ export const subscribeToClientEvents = (messageBus: MessageBus<Events>): void =>
 
   if (appIsAngularInDevMode() && appIsSupportedAngularVersion()) {
     setupInspector(messageBus);
-    onChangeDetection(() => messageBus.emit('componentTreeDirty'));
+    // Often websites have `scroll` event listener which triggers
+    // Angular's change detection. We don't want to constantly send
+    // update requests, instead we want to request an update at most
+    // every 50ms
+    onChangeDetection$.pipe(debounceTime(50)).subscribe(() => messageBus.emit('componentTreeDirty'));
   }
 };
 

projects/ng-devtools/src/lib/devtools-tabs/directive-explorer/directive-explorer.component.ts

@@ -55,6 +55,8 @@ export class DirectiveExplorerComponent implements OnInit {
 
   private _changeSize = new Subject<Event>();
   private _clickedElement: IndexedNode | null = null;
+  private _refreshRetryTimeout: any = null;
+
   parents: FlatNode[] | null = null;
 
   @ViewChild(DirectiveForestComponent) directiveForest: DirectiveForestComponent;
@@ -114,8 +116,15 @@ export class DirectiveExplorerComponent implements OnInit {
 
   refresh(): void {
     const success = this._messageBus.emit('getLatestComponentExplorerView', [this._constructViewQuery()]);
-    if (!success) {
-      setTimeout(() => this.refresh(), 500);
+    // If the event was not throttled, we no longer need to retry.
+    if (success) {
+      clearTimeout(this._refreshRetryTimeout);
+      this._refreshRetryTimeout = null;
+      return;
+    }
+    // If the event was throttled and we haven't scheduled a retry yet.
+    if (!this._refreshRetryTimeout) {
+      this._refreshRetryTimeout = setTimeout(() => this.refresh(), 500);
     }
   }