繼續流之後訂閱

Question

我有兩個流，看起來如下：

const source1 = Rx.Observable.of([1,2,3,4,5]) 
    .map(() => "I am source 1") 
    .do((x) => console.log(x)); 
const sub1 = source1.subscribe((v) => console.log("Subscribe 2")); 

const source2 = Rx.Observable.fromEvent(document, 'click') 
    .do(() => console.log("execute!")) 
    .switchMapTo(source1) 
    .do(() => console.log("After switch map.")) 
    .map((x) => "source2"); 

source2.subscribe((x) => console.log(x)); 

沒有點擊文件我有以下的輸出：

"I am source 1" 
"Subscribe 2" 

而且點擊的輸出是：

"execute!" 
"I am source 1" 
"After switch map." 
"source2" 

如何強制流source1通過進一步點擊和繼續流source2？

我經過以下幾個輸出點擊期望：

"I am source 1" 
"Subscribe 2" 
"execute!" 
"I am source 1" 
"After switch map." 
"source2" 

Answer 1

觀測量可以被認爲是功能。訂閱就像調用函數一樣。

即

const o = Rx.Observable.of(1); 
o.subscribe(x => console.log(x)); 

是非常相似的

const f =() => 1; 
console.log (f()); 

就像調用一個函數不修改功能。訂閱Observable不會修改觀察值。訂閱不是附加任何方式的Observable。它是持有任何狀態的退回訂閱。

---

兩個呼叫在你的榜樣訂閱是完全獨立的，是與此相同：

const source1 = Rx.Observable.of([1,2,3,4,5]) 
    .map(() => "I am source 1") 
    .do((x) => console.log(x)); 
const sub1 = source1.subscribe((v) => console.log("Subscribe 2")); 

const source1_v2 = Rx.Observable.of([1,2,3,4,5]) 
    .map(() => "I am the same as source 1") 
    .do((x) => console.log(x)); 

const source2 = Rx.Observable.fromEvent(document, 'click') 
    .do(() => console.log("execute!")) 
    .switchMapTo(source1_v2) 
    .do(() => console.log("After switch map.")) 
    .map((x) => "source2"); 

source2.subscribe((x) => console.log(x));