RxJS：Observable.form（[arr]）。map（m =＆gt; {...}）---行为解释

Question

我有这段代码：

let myArr = [{a: 'Apple'}, {a: 'Banana'}, {a: 'Carrot'}];

let stream = Observable
    .from(myArr)
    .map( el => {
        el.a = 'Coke';
        console.log(`interim----- ${el} ||| ${myArr}`);
        return el;
    });

stream.subscribe( elm = > elm ));   // to trigger the stream

控制台输出是：

> interim----- {a: "Coke"} ||| [{a: "Coke"}, {a: "Coke"}, {a: "Coke"}]
> interim----- {a: "Coke"} ||| [{a: "Coke"}, {a: "Coke"}, {a: "Coke"}]
> interim----- {a: "Coke"} ||| [{a: "Coke"}, {a: "Coke"}, {a: "Coke"}]

来自＆＃39;来自＆＃39;通过＆＃39; map＆＃39;逐个流式传输数组元素，所以应该在＆＃39; map＆＃39;内同步执行匿名函数。一个一个地改变myArr对象。因此，我的期望是这样的日志，但似乎并非如此，为什么呢？

> interim----- {a: "Coke"} ||| [{a: "Coke"}, {a: "Banana"}, {a: "Carrot"}]   // diff
> interim----- {a: "Coke"} ||| [{a: "Coke"}, {a: "Coke"}, {a: "Carrot"}]     // diff
> interim----- {a: "Coke"} ||| [{a: "Coke"}, {a: "Coke"}, {a: "Coke"}]