标签：The pre ext ror wrap end log from inner
Understanding sources and subscribers makes it much easier to understand what‘s going on with mergeMap under the hood. Where a typical operator invokes destination.next directly, mergeMap wraps destination.next inside of a new source/subscriber combo so there‘s an "outer" next and an "inner" next.
import { fromEvent, of, Subscriber } from "rxjs"
import {
scan,
delay,
mergeMap
} from "rxjs/operators"
class MyMergeMapSubscriber extends Subscriber {
constructor(sub, fn) {
super(sub)
this.fn = fn
}
_next(value) {
console.log(`outer`, value)
const o$ = this.fn(value)
o$.subscribe({
next: value => {
console.log(` inner`, value)
this.destination.next(value)
}
})
}
}
const myMergeMap = fn => source =>
source.lift({
call(sub, source) {
source.subscribe(
new MyMergeMapSubscriber(sub, fn)
)
}
})
const observable$ = fromEvent(
document,
"click"
).pipe(
scan(i => i + 1, 0),
myMergeMap(value => of(value).pipe(delay(500)))
)
const subscriber = {
next: value => {
console.log(value)
},
complete: () => {
console.log("done")
},
error: value => {
console.log(value)
}
}
observable$.subscribe(subscriber)
[RxJS] Implement RxJS `mergeMap` through inner Observables to Subscribe and Pass Values Through
标签：The pre ext ror wrap end log from inner
原文地址：https://www.cnblogs.com/Answer1215/p/9715051.html
