Angular material自动完成，初始化过滤选项以查看焦点上的所有选项

import { MatAutocompleteModule } from '@angular/material/autocomplete';

@NgModule({
  imports: [
    // 其他模块导入
    MatAutocompleteModule
  ],
  // 其他配置
})
export class AppModule { }

<input type="text" matInput [formControl]="myControl" [matAutocomplete]="auto">
<mat-autocomplete #auto="matAutocomplete">
  <mat-option *ngFor="let option of filteredOptions | async" [value]="option">
    {{ option }}
  </mat-option>
</mat-autocomplete>

import { Component } from '@angular/core';
import { FormControl } from '@angular/forms';
import { Observable } from 'rxjs';
import { startWith, map } from 'rxjs/operators';

@Component({
  // 组件配置
})
export class MyComponent {
  myControl = new FormControl();
  options: string[] = ['Option 1', 'Option 2', 'Option 3'];
  filteredOptions: Observable<string[]>;

  constructor() {
    this.filteredOptions = this.myControl.valueChanges.pipe(
      startWith(''),
      map(value => this._filter(value))
    );
  }

  private _filter(value: string): string[] {
    const filterValue = value.toLowerCase();
    return this.options.filter(option => option.toLowerCase().includes(filterValue));
  }
}