What is pipe for in rxJS

Question

I think I have the base concept, but there are some obscurities

So in general this is how I use an observable:

Answer 1

The pipe method

According to original Documentation

the pipable operator is that function take observables as a input and it returns another observable .previous observable stays unmodified.

pipe(...fns: UnaryFunction[]): UnaryFunction

Original Post

What pipe mean?

That means that any operators you previously used on the instance of observable are available as pure functions under rxjs/operators. This makes building a composition of operators or re-using operators becomes really easy, without having to resort to all sorts of programming gymnastics where you have to create a custom observable extending Observable, then overwrite lift just to make your own custom thing.

const { Observable } = require('rxjs/Rx')
const { filter, map, reduce,  } = require('rxjs/operators')
const { pipe } = require('rxjs/Rx')

const filterOutWithEvens = filter(x => x % 2)
const doubleByValue = x => map(value => value * x);
const sumValue = reduce((acc, next) => acc + next, 0);
const source$ = Observable.range(0, 10)

source$.pipe(
  filterOutWithEvens, 
  doubleByValue(2), 
  sumValue)
  .subscribe(console.log); // 50