如何在angular 7中获取selectedIndex值并追加到其他文本框值中

<select [(ngModel)]="selectedOption">
  <option value="option1">Option 1</option>
  <option value="option2">Option 2</option>
  <option value="option3">Option 3</option>
</select>

import { Component, ViewChild, ElementRef } from '@angular/core';

@Component({
  selector: 'app-your-component',
  templateUrl: './your-component.html',
  styleUrls: ['./your-component.css']
})
export class YourComponent {
  @ViewChild('selectElement') selectElement: ElementRef;
  selectedOption: string;

  // 其他代码...
}

import { Component, ViewChild, ElementRef } from '@angular/core';

@Component({
  selector: 'app-your-component',
  templateUrl: './your-component.html',
  styleUrls: ['./your-component.css']
})
export class YourComponent {
  @ViewChild('selectElement') selectElement: ElementRef;
  selectedOption: string;

  onOptionChange() {
    const selectedIndex = this.selectElement.nativeElement.selectedIndex;
    const otherTextBoxValue = '其他文本框的值'; // 替换为你要追加的其他文本框的值
    const newValue = otherTextBoxValue + selectedIndex.toString();

    // 将新的值设置给其他文本框
    // 例如：
    // this.otherTextBoxValue = newValue;
  }

  // 其他代码...
}

<select [(ngModel)]="selectedOption" (change)="onOptionChange()" #selectElement>
  <option value="option1">Option 1</option>
  <option value="option2">Option 2</option>
  <option value="option3">Option 3</option>
</select>