ngIf 跟 else 實作

src/app/app.component.html

@@ -1,5 +1,10 @@
-<button type="button" (click)="onReset()">重設工作事項</button>
-<app-task
-*ngFor="let task of tasks; trackBy: trackByItems"
-[task]="task"
-></app-task>
+<button type="button" (click)="onLoad()">載入資料</button>
+<button type="button" (click)="onClear()">清除資料</button>
+
+<div *ngIf="tasks.length >= 1; else empty">
+  <app-task *ngFor="let task of tasks; let odd = odd" [class.odd]="odd" [task]="task"></app-task>
+</div>
+
+<ng-template #empty>
+  <div class="data-empty">無待辦事項</div>
+</ng-template>

src/app/app.component.spec.ts

@@ -1,35 +0,0 @@
-import { TestBed } from '@angular/core/testing';
-import { RouterTestingModule } from '@angular/router/testing';
-import { AppComponent } from './app.component';
-
-describe('AppComponent', () => {
-  beforeEach(async () => {
-    await TestBed.configureTestingModule({
-      imports: [
-        RouterTestingModule
-      ],
-      declarations: [
-        AppComponent
-      ],
-    }).compileComponents();
-  });
-
-  it('should create the app', () => {
-    const fixture = TestBed.createComponent(AppComponent);
-    const app = fixture.componentInstance;
-    expect(app).toBeTruthy();
-  });
-
-  it(`should have as title 'Learn'`, () => {
-    const fixture = TestBed.createComponent(AppComponent);
-    const app = fixture.componentInstance;
-    expect(app.title).toEqual('Learn');
-  });
-
-  it('should render title', () => {
-    const fixture = TestBed.createComponent(AppComponent);
-    fixture.detectChanges();
-    const compiled = fixture.nativeElement as HTMLElement;
-    expect(compiled.querySelector('.content span')?.textContent).toContain('Learn app is running!');
-  });
-});

src/app/app.component.ts

@@ -1,28 +1,29 @@
-import { Component } from '@angular/core';
+import { Component, OnInit } from '@angular/core';
 
 import { Task } from './task';
 
 @Component({
   selector: 'my-app',
   templateUrl: './app.component.html',
-  styleUrls: [ './app.component.css' ]
+  styleUrls: ['./app.component.css'],
 })
-export class AppComponent  {
-  tasks: Task[] = [
+export class AppComponent implements OnInit {
+  tasks!: Task[];
+
+  ngOnInit(): void {
+    this.onLoad();
+  }
+
+  onLoad(): void {
+    this.tasks = [
       new Task({ TaskSn: '001', TaskName: '待辦事項 A', State: 'Finish' }),
       new Task({ TaskSn: '002', TaskName: '待辦事項 B', State: 'Doing' }),
       new Task({ TaskSn: '003', TaskName: '待辦事項 C', State: 'None' }),
       new Task({ TaskSn: '004', TaskName: '待辦事項 D', State: 'None' }),
     ];
-  trackByItems(index:number, task:Task):string{
-    return task.TaskSn;
   }
-  onReset():void{
-    this.tasks=[
-      new Task({ TaskSn: '001', TaskName: '待辦事項 A', State: 'Finish' }),
-      new Task({ TaskSn: '002', TaskName: '待辦事項 B', State: 'Doing' }),
-      new Task({ TaskSn: '004', TaskName: '待辦事項 C', State: 'None' }),
-      new Task({ TaskSn: '005', TaskName: '待辦事項 D', State: 'None' }),
-    ];
+
+  onClear(): void {
+    this.tasks = [];
   }
 }