背景

为了做一个面包屑的样式

思路

三个界面：
根页面: index（展示面包屑）
资金页面: fund(展示收入、支出，属于同一个页面)

步骤：
在index服务中存BehaviorSubject类型的变量crumbData，
在found组件中监听路由变化，根据路由参数设置不同的面包屑数据，
在index组件中订阅crumbData变量

出现的问题：
如果不用BehaviorSubject订阅，直接设为一个列表，在更新时，会报错:数据已经检查后被修改
ExpressionChangedAfterItHasBeenCheckedError: Expression has changed after it was checked.

源码

src\app\pages\index\index.component.html

	<li nz-menu-item (click)="navigate('/found', 0)">村收入</li>
    <li nz-menu-item (click)="navigate('/found', 1)">村支出</li>
    
    <nz-breadcrumb>
      <ng-container *ngFor="let item of crumbData">
        <nz-breadcrumb-item >{{item}}</nz-breadcrumb-item>
      </ng-container>
    </nz-breadcrumb>
    
	<router-outlet></router-outlet>

src\app\pages\index\index.component.ts

import { Component, OnInit } from '@angular/core';
import { Router } from '@angular/router';
declare const document: any;
import { IndexService } from './index.service';

@Component({
  selector: 'k-index',
  templateUrl: './index.component.html',
  styleUrls: ['./index.component.scss']
})
export class IndexComponent{

  constructor(
    private route: Router,
    public indexService: IndexService,
    ) { 
      this.indexService.crumbData.subscribe((x) => {
        this.crumbData = x
    });
    }
    
  // 面包屑数据
  public crumbData: any = ['首页']

  navigate(url: any, type?: any) {
    this.route.navigate([url], { queryParams: { type: type } })
  }
}

src\app\pages\index\index.service.ts

import { Injectable } from '@angular/core';
import { BehaviorSubject } from 'rxjs';

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

  // 面包屑数据
  public crumbData = new BehaviorSubject<any>(['首页']);

  setData(data: any) {
    this.crumbData.next(data);
  }
}

参考

vue、angular中的数据监听