在学习如何在Angular中实现文字逐字显示的过程中，我发现要保证用户的体验感的关键点在于：如何确保实时更新.html页面的内容显示，保证及时在UI界面反应出后端返回的数据?  那如何解决这个问题呢？其实我在博客中有提到过这个问题的解决办法，大家有兴趣可以去帮忙简单的检阅一下：https://blog.csdn.net/qq_44327851/article/details/135152188

        下面是上面博客的进阶版学习---->这篇博客主要是文字逐字显示过程页面实时更新的解决办法，话不多说，直接上代码。

1. 使用setTimeout函数创建定时器，更新文字显示，并手动触发变更检测：

   import { Component, ChangeDetectorRef } from '@angular/core';@Component({selector: 'app-root',template: `<div>{{ displayedText }}</div>`
   })
   export class AppComponent {text = 'Hello World';displayedText = '';currentIndex = 0;constructor(private cdr: ChangeDetectorRef) {}ngOnInit() {const updateText = () => {this.displayedText = this.text.slice(0, this.currentIndex + 1);this.currentIndex++;this.cdr.detectChanges();if (this.currentIndex < this.text.length) {setTimeout(updateText, 1000);}};updateText();}
   }
   

2. 使用NgZone服务在NgZone之外运行文字更新逻辑：

   import { Component, NgZone } from '@angular/core';@Component({selector: 'app-root',template: `<div>{{ displayedText }}</div>`
   })
   export class AppComponent {text = 'Hello World';displayedText = '';currentIndex = 0;constructor(private zone: NgZone) {}ngOnInit() {this.zone.runOutsideAngular(() => {const interval = setInterval(() => {this.zone.run(() => {this.displayedText = this.text.slice(0, this.currentIndex + 1);this.currentIndex++;});if (this.currentIndex === this.text.length) {clearInterval(interval);}}, 1000);});}
   }
   

3. 使用OnPush变更检测策略和markForCheck方法：

   import { Component, ChangeDetectorRef, ChangeDetectionStrategy } from '@angular/core';@Component({selector: 'app-root',template: `<div>{{ displayedText }}</div>`,changeDetection: ChangeDetectionStrategy.OnPush
   })
   export class AppComponent {text = 'Hello World';displayedText = '';currentIndex = 0;constructor(private cdr: ChangeDetectorRef) {}ngOnInit() {const interval = setInterval(() => {this.displayedText = this.text.slice(0, this.currentIndex + 1);this.currentIndex++;this.cdr.markForCheck();if (this.currentIndex === this.text.length) {clearInterval(interval);}}, 1000);}
   }
   

4. 使用AsyncPipe结合Observable实现文字逐字显示：

   import { Component } from '@angular/core';
   import { timer } from 'rxjs';@Component({selector: 'app-root',template: `<div>{{ (text$ | async) }}</div>`
   })
   export class AppComponent {text = 'Hello World';text$ = timer(0, 1000).pipe(map(index => this.text.slice(0, index + 1)),take(this.text.length));
   }
   

5. 使用Renderer2服务手动更新DOM元素的innerText属性：

   import { Component, Renderer2, ElementRef } from '@angular/core';@Component({selector: 'app-root',template: `<div #textElement></div>`
   })
   export class AppComponent {text = 'Hello World';currentIndex = 0;constructor(private renderer: Renderer2, private el: ElementRef) {}ngOnInit() {const interval = setInterval(() => {this.renderer.setProperty(this.el.nativeElement, 'innerText', this.text.slice(0, this.currentIndex + 1));this.currentIndex++;if (this.currentIndex === this.text.length) {clearInterval(interval);}}, 1000);}
   }
   

6. 使用ViewChild装饰器获取DOM元素的引用，直接操作DOM元素实现文字逐字显示：

   import { Component, ViewChild, ElementRef } from '@angular/core';@Component({selector: 'app-root',template: `<div #textElement></div>`
   })
   export class AppComponent {@ViewChild('textElement', { static: true }) textElement: ElementRef;text = 'Hello World';currentIndex = 0;ngOnInit() {const interval = setInterval(() => {this.textElement.nativeElement.innerText = this.text.slice(0, this.currentIndex + 1);this.currentIndex++;if (this.currentIndex === this.text.length) {clearInterval(interval);}}, 1000);}
   }
   

7. 使用NgZone服务结合setTimeout函数实现文字逐字显示：

   import { Component, NgZone } from '@angular/core';@Component({selector: 'app-root',template: `<div>{{ displayedText }}</div>`
   })
   export class AppComponent {text = 'Hello World';displayedText = '';currentIndex = 0;constructor(private zone: NgZone) {}ngOnInit() {this.zone.runOutsideAngular(() => {const updateText = () => {this.displayedText = this.text.slice(0, this.currentIndex + 1);this.currentIndex++;if (this.currentIndex < this.text.length) {setTimeout(updateText, 1000);}};updateText();});}
   }
   

8. 使用ElementRef服务直接操作DOM元素实现文字逐字显示：

   import { Component, ElementRef } from '@angular/core';@Component({selector: 'app-root',template: `<div #textElement></div>`
   })
   export class AppComponent {constructor(private el: ElementRef) {}ngOnInit() {const textElement = this.el.nativeElement.querySelector('#textElement');const text = 'Hello World';let currentIndex = 0;const interval = setInterval(() => {textElement.innerText = text.slice(0, currentIndex + 1);currentIndex++;if (currentIndex === text.length) {clearInterval(interval);}}, 1000);}
   }
   

9. 使用Renderer2服务创建文本节点，逐步添加到DOM元素中实现文字逐字显示：

   import { Component, Renderer2, ElementRef } from '@angular/core';@Component({selector: 'app-root',template: `java<div #textElement></div>`
   })
   export class AppComponent {text = 'Hello World';currentIndex = 0;constructor(private renderer: Renderer2, private el: ElementRef) {}ngOnInit() {const textElement = this.el.nativeElement.querySelector('#textElement');const text = 'Hello World';const interval = setInterval(() => {const textNode = this.renderer.createText(text.slice(0, this.currentIndex + 1));this.renderer.appendChild(textElement, textNode);this.currentIndex++;if (this.currentIndex === text.length) {clearInterval(interval);}}, 1000);}
   }
   

10. 使用@Input装饰器监听输入属性的变化，更新文字显示：

    import { Component, Input } from '@angular/core';@Component({selector: 'app-root',template: `<div>{{ displayedText }}</div>`
    })
    export class AppComponent {@Input() text: string;displayedText = '';currentIndex = 0;ngOnInit() {const interval = setInterval(() => {this.displayedText = this.text.slice(0, this.currentIndex + 1);this.currentIndex++;if (this.currentIndex === this.text.length) {clearInterval(interval);}}, 1000);}
    }