zhukejin/blogs

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blogs's Issues

事件流

事件传播三阶段：
1.capture phase （事件捕获）
2.target phase （处于目标）
3.bubbling phase （事件冒泡）
在 target phase，event handler 被调用的顺序不再遵循先捕获，后冒泡的原则，而是严格按照 event handler 注册的顺序，先注册，故而先执行。要改变二者的执行顺序，只需要改变两段源码的顺序即可。
W3C 规范：
Next, the implementation must determine the current target's candidate event listeners. This must be the list of all event listeners that have been registered on the current target in their order of registration. [HTML5] defines the ordering of listeners registered through event handler attributes. Once determined, the candidate event listeners must not be changed. Adding or removing listeners does not affect the current target's candidate event listeners.
https://stackoverflow.com/questions/18103391/usecapture-in-addeventlistener-behaves-strangely?lq=1
https://stackoverflow.com/questions/11841330/event-listeners-registered-for-capturing-phase-not-triggered-before-bubbling-w

我的理解

捕捉是dom元素向后代下沉的过程，冒泡是相反，因此，捕捉和dom的加载顺序是一直的，在dom加载的过程中触发捕捉事件，而冒泡必须在加载完成后才会触发。这样理解就很好理解作者的实验项目了

blogs/JAVASCRIPT/Javascript-event.md的另一观点

window (1) -> document (1) -> body (1) -> ul (1) -> li -> ul (2) -> body (2) -> document (2) -> window (2)

在浏览器支持addEventListener的前提下
addEventListener(ul, function(){}, true)
// 这里的ul, 是 ul(1)
addEventListener(ul, function(){}, false)
// 这里的ul, 是 ul(2)

我的看法，这样理解才更加正确