如何将多个监听器分配给单个StreamSubscription？ [英] How can you assign mutliple listeners to a single StreamSubscription?

问题描述

这是有效的语句

StreamSubscription currentSubscription = querySelector(…).onClick.listen(….).

这里有一个监听器分配给一个StreamSubscription。

here there is one listener that is assigned to one StreamSubscription.

但是当你做一个queryselectorAll（..）。onClick.listen（..）。

But when you do a queryselectorAll(..).onClick.listen(..) . You are adding listeners to all the query selected elements.

我注意到以下语句也有效。

I noticed that the following statement is also valid.

StreamSubscription currentSubscription = queryselectorAll(..).onClick.listen(..) 

在这里，我将一个1 StreamSubscription分配给带有onClick侦听器的元素列表。

Here, I am assigning a 1 StreamSubscription to a list of elements with onClick listeners. How does this work?

推荐答案

您不能将多个侦听器分配给 StreamSubscription 。

You can't assign multiple listeners to a StreamSubscription.

您的第二个语句不起作用，因为 querySelectorAll（）返回一个集合，

Your 2nd statement doesn't work because querySelectorAll() returns a collection and you can't listen to a collection.

也许这是你想要的：

Iterable<StreamSubscription> subscriptions = 
    queryselectorAll(..).map((e) => e.onClick.listen(..));

后来

if(subscriptions != null) {
  subscriptions.forEach((s) => s.cancel());
}

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