在Angular 2中有没有聪明的方法返回到最后一页?

类似的

this._router.navigate(LASTPAGE);

例如,C页有一个“返回”按钮,

A页-> C页,点击返回A页。 B页-> C页,点击它,回到B页。

路由器有这个历史信息吗?


当前回答

用Angular 5.2.9测试过

如果你使用锚而不是按钮,你必须使用href="javascript:void(0)"将其设置为被动链接,以使Angular Location正常工作。

app.component.ts

import { Component } from '@angular/core';
import { Location } from '@angular/common';

@Component({
  selector: 'app-root',
  templateUrl: './app.component.html',
  styleUrls: [ './app.component.css' ]
})
export class AppComponent {

  constructor( private location: Location ) { 
  }

  goBack() {
    // window.history.back();
    this.location.back();

    console.log( 'goBack()...' );
  }
}

app.component.html

<!-- anchor must be a passive link -->
<a href="javascript:void(0)" (click)="goBack()">
  <-Back
</a>

其他回答

在这些精彩的答案之后,我希望我的答案能找到一些人,并帮助他们。我编写了一个小服务来跟踪路线历史。开始了。

import { Injectable } from '@angular/core';
import { NavigationEnd, Router } from '@angular/router';
import { filter } from 'rxjs/operators';

@Injectable()
export class RouteInterceptorService {
  private _previousUrl: string;
  private _currentUrl: string;
  private _routeHistory: string[];

  constructor(router: Router) {
    this._routeHistory = [];
    router.events
      .pipe(filter(event => event instanceof NavigationEnd))
      .subscribe((event: NavigationEnd) => {
        this._setURLs(event);
      });
  }

  private _setURLs(event: NavigationEnd): void {
    const tempUrl = this._currentUrl;
    this._previousUrl = tempUrl;
    this._currentUrl = event.urlAfterRedirects;
    this._routeHistory.push(event.urlAfterRedirects);
  }

  get previousUrl(): string {
    return this._previousUrl;
  }

  get currentUrl(): string {
    return this._currentUrl;
  }

  get routeHistory(): string[] {
    return this._routeHistory;
  }
}

是的,你能做到。在你的typescript组件上编写这段代码,然后享受吧!

import { Location } from '@angular/common'
import { Component, Input } from '@angular/core'

@Component({
    selector: 'return_page',
    template: `<button mat-button (click)="onReturn()">Back</button>`,
})
export class ReturnPageComponent {
  constructor(private location: Location) { }

  onReturn() {
    this.location.back();
  }
}

这是我想出来的,你也可以查一下是否有上一页。 确保在你的appComponent中使用了这个服务。

import { Injectable } from '@angular/core';
import { Location } from '@angular/common';
import { NavigationEnd, Router } from '@angular/router';

interface HistoryData {
  previousPage: string | null,
  currentPage: string | null,
}

@Injectable({ providedIn: 'root' })
export class GoBackService {

  private historyData: HistoryData = { previousPage: null, currentPage: null };

  constructor(private router: Router, private location: Location) {
    this.router.events.subscribe((event) => {
      if (event instanceof NavigationEnd) {
        this.historyData.previousPage = this.historyData.currentPage;
        this.historyData.currentPage = event.urlAfterRedirects;
      }
    });
  }

  public goBack(): void {
    if (this.historyData.previousPage) this.location.back();
  }

  public canGoBack(): boolean {
    return Boolean(this.historyData.previousPage);
  }

}

检测到的未更改组件的@Parziphal答案版本:

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

  constructor(private readonly router: Router, private readonly location: Location) {
    location.onUrlChange(() => this.canGoBack = !!this.router.getCurrentNavigation()?.previousNavigation);
  }

  goBack(): void {
    if (this.canGoBack) {
      this.location.back();
    }
  }

<按钮返回按钮>返回</button>

你可以把它放到一个指令中,这个指令可以附加到任何可点击的元素上:

import { Directive, HostListener } from '@angular/core';
import { Location } from '@angular/common';

@Directive({
    selector: '[backButton]'
})
export class BackButtonDirective {
    constructor(private location: Location) { }

    @HostListener('click')
    onClick() {
        this.location.back();
    }
}

用法:

<button backButton>BACK</button>