在Angular 6中导航到back page时如何清除dropdowns值

import { FormGroup, FormControl } from '@angular/forms';

export class YourComponent {
  form: FormGroup;

  constructor() {
    this.form = new FormGroup({
      dropdownValue: new FormControl('default value')
    });
  }
}

<select [(ngModel)]="form.controls.dropdownValue.value">
  <option value="value1">Value 1</option>
  <option value="value2">Value 2</option>
  <option value="value3">Value 3</option>
</select>

import { Router } from '@angular/router';

export class YourComponent {
  constructor(private router: Router) {}

  navigateToBackPage() {
    // 清除dropdown的值
    this.form.reset();

    // 导航到back page
    this.router.navigate(['/back-page']);
  }
}