获取上一个页面的url

Angular6更新了获取前一个URL作为字符串的代码。

import { Component, OnInit } from '@angular/core';
import { Router, RoutesRecognized } from '@angular/router';
import { filter, pairwise } from 'rxjs/operators';
export class AppComponent implements OnInit {
    constructor (
        public router: Router
    ) {
    }
    ngOnInit() {
        this.router.events
            .pipe(filter((e: any) => e instanceof RoutesRecognized),
                pairwise()
            ).subscribe((e: any) => {
                console.log(e[0].urlAfterRedirects); // previous url
            });
    }