Don’t get confused with the concepts of Angular and RxJS We have pipes concept in Angular and pipe() function in RxJS. 1) Pipes in Angular: A pipe takes in data as input and transforms it to the desired output https://angular.io/guide/pipes 2) pipe() function in RxJS: You can use pipes to link operators together. Pipes let … Read more
Here is where you went wrong: this.result = http.get(‘friends.json’) .map(response => response.json()) .subscribe(result => this.result =result.json()); it should be: http.get(‘friends.json’) .map(response => response.json()) .subscribe(result => this.result =result); or http.get(‘friends.json’) .subscribe(result => this.result =result.json()); You have made two mistakes: 1- You assigned the observable itself to this.result. When you actually wanted to assign the list of … Read more
This might be helpful in Angular 6 for more info refer this Document rxjs: Creation methods, types, schedulers and utilities import { Observable, Subject, asapScheduler, pipe, of, from, interval, merge, fromEvent } from ‘rxjs’; rxjs/operators: All pipeable operators: import { map, filter, scan } from ‘rxjs/operators’; rxjs/webSocket: The web socket subject implementation import { webSocket … Read more
You need to import the map operator: import ‘rxjs/add/operator/map’
Actually I have imports messed up. In latest version of RxJS we can import it like that: import ‘rxjs/add/observable/of’;
Operators first() and take(1) aren’t the same. The first() operator takes an optional predicate function and emits an error notification when no value matched when the source completed. For example this will emit an error: import { EMPTY, range } from ‘rxjs’; import { first, take } from ‘rxjs/operators’; EMPTY.pipe( first(), ).subscribe(console.log, err => console.log(‘Error’, … Read more
It is important to note the difference between of and from when passing an array-like structure (including strings): Observable.of([1, 2, 3]).subscribe(x => console.log(x)); would print the whole array at once. On the other hand, Observable.from([1, 2, 3]).subscribe(x => console.log(x)); prints the elements 1 by 1. For strings the behaviour is the same, but at character … Read more
It really comes down to behavior and semantics. With a Subject – a subscriber will only get published values that were emitted after the subscription. Ask yourself, is that what you want? Does the subscriber need to know anything about previous values? If not, then you can use this, otherwise choose one of the others. … Read more
Not 100% certain about what you need, but if you only want to observe the first value, then use either first() or take(1): observable.first().subscribe(func); note: .take(1) and .first() both unsubscribe automatically when their condition is met Update from RxJS 5.5+ From comment by Coderer. import { first } from ‘rxjs/operators’ observable .pipe(first()) .subscribe(func); Here’s why
With the new syntax of RxJS 5.5+, this becomes as the following: // RxJS 6 import { EMPTY, empty, of } from “rxjs”; // rxjs 5.5+ (<6) import { empty } from “rxjs/observable/empty”; import { of } from “rxjs/observable/of”; empty(); // deprecated use EMPTY EMPTY; of({}); Just one thing to keep in mind, EMPTY completes … Read more