确保 jQuery 事件处理程序执行顺序

问题描述

我认为事件处理程序是按照它们注册的顺序处理的.(对吗?)如果是这种情况，那么如果我在脚本的开头附加一个事件处理程序，我可以绝对确定它会在附加到同一事件的后续处理程序之前触发吗?事件命名空间也对此有任何影响吗?事件处理程序是串行触发(一个在下一个完成之前完成)还是并行触发?

I think that event handlers are processed in the order that they are registered. (Is that correct?) If that is the case then if I attach an event handler at the beginning of my script, can I be absolutely certain that it will fire before subsequent handlers attached to the same event? Also do event namespaces have any effect on this? Are event handlers fired in series (one finishes before the next) or in parallel?

我想这样做是因为我的脚本依赖于视口大小，视口大小会随着 resize 事件发生变化，我需要不断地寻找它.我不想在我的每个处理函数中重复调用 $(window).width()，而是想在我的脚本顶部放置一个处理程序来保存 $(window).width() 在每次调整大小时添加到对象属性.然后在后续处理程序中，我可以访问该属性并确定它是最新的测量值.

I want to do this because my script relies on the viewport size, which changes on the resize event, and I need to constantly look for it. Rather than calling $(window).width() repeatedly in each of my handler functions, I'd like to put a handler at the top of my script that saves $(window).width() to an object property on each resize. Then in subsequent handlers I can access the property and be certain that it is the most recent measurement.

我知道我可以创建一个在计算完成后立即触发的自定义事件，并将后续处理程序附加到自定义事件.但是，我不想这样做，因为我需要保持与我之后的插件的互操作性，这些插件也可能附加到调整大小事件.

I know I could create a custom event that triggers as soon as the calculation is done and attach subsequent handlers to the custom event. But, I'd don't want to do that because I need to maintain interoperability with plugins that come after mine that may also be attaching to the resize event.

推荐答案

如果您在任何其他脚本(甚至只是一个插件)运行之前附加您的事件处理程序，那么您的回调将始终首先触发.

If you attach your event handler before any other script has run (even just a plugin), then your callback will always fire first.

您可以通过数据对象检查事件处理程序数组:

You can inspect the array of event handlers through the data object:

$(window).data('events');

注意:这是一种未记录的方法，最终可能不起作用.仅用于检查.

Note: this is a non-documented approach and might not work eventually. Use it for inspection only.

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