I'm using RxJS v7.
I noticed when I create new observable from scratch or using map, scan, merge or other operators, the observable called multiple times unless using share if I use a variable holding it multiple times. Like below
let share_a = false
let share_b = false
if (process.argv[2] === 'share_a') {
share_a = true
}
if (process.argv[3] === 'share_b') {
share_b = true
}
console.log({ share_a, share_b })
const { map, merge, tap, share, Observable } = require('rxjs')
const sleep = ms => new Promise(resolve => setTimeout(resolve, ms))
let a = new Observable(async subscriber => {
await sleep(100)
console.log('a called')
subscriber.next('a')
})
if (share_a) {
a = a.pipe(share())
}
let b = a.pipe(map(() => 'b'), tap(x => console.log(`${x} called`)))
if (share_b) {
b = b.pipe(share())
}
const c = merge(a, b).pipe(map(() => 'c'), tap(x => console.log(`${x} called`)))
merge(a,b,c).subscribe(console.log)
% node src/rxjsTest.js
{ share_a: false, share_b: false }
a called
a
a called
b called
b
a called
c called
c
a called
b called
c called
c
% node src/rxjsTest.js share_a
{ share_a: true, share_b: false }
a called
a
b called
b
c called
c
b called
c called
c
% node src/rxjsTest.js share_a share_b
{ share_a: true, share_b: true }
a called
a
b called
b
c called
c
c called
c
%
How can I make every observable shared without calling share every time?
