Working on figure out the cause of high cpu usage.

Author: gnu4cn

src/app/home/home.page.html

@@ -110,9 +110,10 @@
     </ion-toolbar>
 </ion-header>
 
-<ion-content 
+<ion-content [scrollEvents]="true"
     fxLayout="row"
     fxLayoutAlign="center start"
+    (ionScroll)="onScroll($event)" 
     style="padding: 10px;">
     <!-- 已下载/保存书籍列表 -->
     <app-book-list *ngIf="!search"

src/app/home/home.page.ts

@@ -9,7 +9,13 @@ import {
     MatDialog, 
 } from '@angular/material/dialog';
 
-import {FormControl, FormGroupDirective, NgForm, Validators} from '@angular/forms';
+import {
+    FormControl, 
+    FormGroupDirective, 
+    NgForm, 
+    Validators
+} from '@angular/forms';
+
 import {ErrorStateMatcher} from '@angular/material/core';
 import {PageEvent} from '@angular/material/paginator';
 
@@ -263,6 +269,25 @@ export class HomePage implements OnInit, AfterViewInit {
         });
     }
 
+    onScroll = async ($event) => {
+        if(!this.search || this.searchEnd){ return; }
+        if($event.target.localName !== 'ion-content') { return; }
+
+        const scrollElement = await $event.target.getScrollElement();
+        const scrollHeight = scrollElement.scrollHeight - scrollElement.clientHeight;
+
+        const currentScrollDepth = $event.detail.scrollTop;
+
+        if(currentScrollDepth === scrollHeight){
+            if(
+                this.bookListCloud.length%20 === 0 
+                && !(/gitlab/.test(this.platformSelected))
+            ){
+                this.cloudSearch(this.bookListCloud.length/20 + 1);
+            }
+        }
+    }
+
     historySearch = (keywords: string, platform: string) => {
         this.keywords = keywords;
         this.platformSelected = platform;

src/polyfills.ts

@@ -1,57 +1,3 @@
-/**
- * This file includes polyfills needed by Angular and is loaded before the app.
- * You can add your own extra polyfills to this file.
- *
- * This file is divided into 2 sections:
- *   1. Browser polyfills. These are applied before loading ZoneJS and are sorted by browsers.
- *   2. Application imports. Files imported after ZoneJS that should be loaded before your main
- *      file.
- *
- * The current setup is for so-called "evergreen" browsers; the last versions of browsers that
- * automatically update themselves. This includes Safari >= 10, Chrome >= 55 (including Opera),
- * Edge >= 13 on the desktop, and iOS 10 and Chrome on mobile.
- *
- * Learn more in https://angular.io/guide/browser-support
- */
-
-/***************************************************************************************************
- * BROWSER POLYFILLS
- */
-
-/** IE10 and IE11 requires the following for NgClass support on SVG elements */
-// import 'classlist.js';  // Run `npm install --save classlist.js`.
-
-/**
- * Web Animations `@angular/platform-browser/animations`
- * Only required if AnimationBuilder is used within the application and using IE/Edge or Safari.
- * Standard animation support in Angular DOES NOT require any polyfills (as of Angular 6.0).
- */
-// import 'web-animations-js';  // Run `npm install --save web-animations-js`.
-
-/**
- * By default, zone.js will patch all possible macroTask and DomEvents
- * user can disable parts of macroTask/DomEvents patch by setting following flags
- * because those flags need to be set before `zone.js` being loaded, and webpack
- * will put import in the top of bundle, so user need to create a separate file
- * in this directory (for example: zone-flags.ts), and put the following flags
- * into that file, and then add the following code before importing zone.js.
- * import './zone-flags.ts';
- *
- * The flags allowed in zone-flags.ts are listed here.
- *
- * The following flags will work for all browsers.
- *
- * (window as any).__Zone_disable_requestAnimationFrame = true; // disable patch requestAnimationFrame
- * (window as any).__Zone_disable_on_property = true; // disable patch onProperty such as onclick
- * (window as any).__zone_symbol__BLACK_LISTED_EVENTS = ['scroll', 'mousemove']; // disable patch specified eventNames
- *
- *  in IE/Edge developer tools, the addEventListener will also be wrapped by zone.js
- *  with the following flag, it will bypass `zone.js` patch for IE/Edge
- *
- *  (window as any).__Zone_enable_cross_context_check = true;
- *
- */
-
 import './zone-flags';
 
 /***************************************************************************************************