RxJS combine最大的困惑

Question

我以爲我明白combineLatest，但給我的輸出 - 我不理解它。我認爲，當所有可觀測量發出時，所有可觀測量都會發出最後的值。

（注：我只是做取（5）來限制我的控制檯輸出）

所以，對於這個簡單的例子 -

const int1$ = Rx.Observable.interval(1000).take(5) 
const int2$ = Rx.Observable.interval(500).take(5) 
const int3$ = Rx.Observable.interval(3000).take(5) 
const all$ = Rx.Observable.combineLatest(
    int1$, int2$, int3$ 
) 

all$.subscribe(latestValues => { 
    const [int1, int2, int3] = latestValues; 
    console.log(` 
     interval one @ 1000 ${int1}, 
     interval two @ 500 ${int2}, 
     interval three @ 3000 ${int3} 
    `) 
}) 

我想看到

" 
     interval one @ 1000 0, 
     interval two @ 500 1, 
     interval three @ 3000 0 
    " 
" 
     interval one @ 1000 1, 
     interval two @ 500 2, 
     interval three @ 3000 0 
    " 
" 
     interval one @ 1000 1, 
     interval two @ 500 3, 
     interval three @ 3000 1 
    " 
" 
     interval one @ 1000 2, 
     interval two @ 500 4, 
     interval three @ 3000 1 

但我越來越

" 
     interval one @ 1000 2, 
     interval two @ 500 4, 
     interval three @ 3000 0 
    " 
" 
     interval one @ 1000 3, 
     interval two @ 500 4, 
     interval three @ 3000 0 
    " 
" 
     interval one @ 1000 4, 
     interval two @ 500 4, 
     interval three @ 3000 0 
    " 
" 
     interval one @ 1000 4, 
     interval two @ 500 4, 
     interval three @ 3000 1 

有些困惑。你對我爲什麼沒有看到我期望的東西的想法會很棒！

Answer 1

http://reactivex.io/documentation/operators/combinelatest.html CombineLatest發出項目每當任何源可觀察量發出項目

（只要每個源可觀察量已發射的至少一個項目）< < == THIS

INT3是在3000毫秒之前沒有發射任何物品，所以Rx等待它，然後用最新物品呼叫onNext

可能的解決方案：嘗試使用計時器代替（在0秒發射第一個值，然後每發射一次）

const int1$ = Rx.Observable.timer(0,1000).take(5) 
const int2$ = Rx.Observable.timer(0,500).take(5) 
const int3$ = Rx.Observable.timer(0,3000).take(5) 
const all$ = Rx.Observable.combineLatest(
    int1$, int2$, int3$ 
) 

all$.subscribe(latestValues => { 
    const [int1, int2, int3] = latestValues; 
    console.log(` 
     interval one @ 1000 ${int1}, 
     interval two @ 500 ${int2}, 
     interval three @ 3000 ${int3} 
    `) 
})