angular2-services

问题 Is there a way to emit event in angular2 that can be listened to in entire application? Like we had in AngularJS using $rootScope.broadcast and emit . Can this same thing be achieved in angular2? I read about @Output() and EventEmitter() and implemented it but it restricts only the parent to listen to the event emmitted by child. I read about BehaviorSubject being one of the ways to do this. Is that the right approach? Any other solution for this? 回答1: In Angular2 there is no global scope.

问题 api.service.ts import { Injectable, Inject } from '@angular/core'; import { Http, Headers } from '@angular/http'; import { Observable } from 'rxjs/Observable'; import 'rxjs/add/observable/throw'; import 'rxjs/add/operator/map'; import 'rxjs/add/operator/catch'; import 'rxjs/add/operator/timeout'; import 'rxjs/add/operator/retry'; import { CacheService } from './cache.service'; import { AuthService } from '../services/auth.service'; import { CookieService } from 'angular2-cookie/core';

问题 I want to create a countdown timer which has 4 fields hours:minutes:seconds:milliseconds. I've gone through the following links before I posted this question.I don't know why should we have a hardcoded date and then subtract something from it. I'm not able to get the concept of Observable here. Time CountDown in angular 2 Angular 2 - Countdown timer Can someone please help me? This is what I've written from https://stackoverflow.com/a/40784539/4579897 private eventDate: Date = new Date(2018,

问题 I writing a service which do a http query to the backend: getPlacesForUser(){ this.http.get("http://localhost:8080/processPlaces") .map(res => res.text()) .subscribe( data => this.result = data, err => this.logError(err), () => console.log('Places Request completed') ) } Now I want to update the components-side, if the request is completed: processPlaces(){ this._backendService.getPlacesForUser(); } How can I communicate between the component and service? Furthermore I searching for the best

问题 I have a service that GETS a user via a RESTful api. It uses the Observable implementation. I also have a parent component with 8 child components. I want to know if and how I can make a single HTTP request in the parent component, to get the user and share it amongst its children components. Here's the call to define user in the parent: this.userApi.getUser(id) .subscribe(response => {this.user = response;}, error => error); I've imported and injected the user model into the constructor() of

问题 How can I use ViewChild in Angular 2 Javascript? I have referred angular.io docs and I have tried with the following code and it is not working. Can anyone help me? Thanks in advance. main.html <router-outlet></router-outlet> app.component.js (function (app) { app.AppComponent = ng.core .Component({ selector: 'my-app', templateUrl: 'app/views/main.html', directives: [ng.router.ROUTER_DIRECTIVES], //<----not loading components here viewProviders: [ng.http.HTTP_PROVIDERS], queries: {

问题 I am new to rxjs, so I would like to ask a question regarding Angular 2 , Observables and BehaviorSubject/Subject . So, what I want to achieve is : onclick of a button inside a ComponentA to notify other components for example ComponentB , ComponentC . What I did so far is to create a service : private isMenuOpenBS = new BehaviorSubject(false); toggleMenu(): void { this.isMenuOpenBS.next(!this.isMenuOpenBS.getValue()); } getMenuState(): Observable<boolean> { return this.isMenuOpenBS

问题 I have ng2-charts working on my Angular-cli built application. I'm pretty new, so any help is appreciated. I have data setup on Firebase. I create a method in a service to access that data and when I use this code getGraphData():Observable<any>{ var graphData$ = this.af.database.list(`graphdata/${this.uid}`) .map(tspa => tspa.map(tpa => tpa.$value)) .do(console.log); graphData$.subscribe(); return Observable.of([]); } the console logs the correct data. ex. [1000, 5000, 2000] the problem is

问题 I have a parent component with two child routes. Each child route will need to use/access the same data retrieved from a GET request. I think it may be wasteful to query the server each time a child route is loaded, so I thought a good way of doing this would be to query the server once through the parent route and then sharing the data afterwards through a bi-directional service, which I'm trying to implement following the angular docs closely. However, neither of the child components are

问题 I cannot get the reason why one of my services always returns undefined however network tab in developer mode shows me that data has been received. Could somebody help me to figure out where my mistake is? My component looks next way: export interface Sponsors { id; sponsorCode; sponsorName; active; clientId; countryId; cloudRegionId; } @Component({ selector: 'app-sponsors', templateUrl: './sponsors.component.html', styleUrls: ['./sponsors.component.css'], }) export class SponsorsComponent