继续流之后订阅

Question

我有两个流，看起来如下：

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)); 

没有点击文件我有以下的输出：

"I am source 1" 
"Subscribe 2" 

而且点击的输出是：

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

如何强制流source1通过进一步点击和继续流source2？

我经过以下几个输出点击期望：

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

Answer 1

观测量可以被认为是功能。订阅就像调用函数一样。

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()); 

就像调用一个函数不修改功能。订阅Observable不会修改观察值。订阅不是附加任何方式的Observable。它是持有任何状态的退回订阅。

---

两个呼叫在你的榜样订阅是完全独立的，是与此相同：

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));