javascript 当网页获得焦点时的事件
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Event when a web page gets focused
提问by Shay Erlichmen
Google Reader has a nice feature that when you switch to the web page from a different web page (giving the page focus) it will show you the updates there were accumulated while the page was unfocused.
Quick question #1: How do they do that?
谷歌阅读器有一个很好的功能，当你从不同的网页切换到网页时（给页面焦点），它会向你显示页面未聚焦时累积的更新。
快速问题#1：他们是怎么做到的？
I figure that they might be binding to the mouse move events + keyboard events since I don't know any out of the box event that gives you that ability.
我认为它们可能会绑定到鼠标移动事件 + 键盘事件，因为我不知道任何能够为您提供这种能力的开箱即用事件。
Googling for that is a nightmare (focus, tab, web page, user).
谷歌搜索是一场噩梦（焦点、标签、网页、用户）。
Quick question #2: Is there some package out there that gives me that ability?
快速问题#2：是否有一些软件包可以赋予我这种能力？
I'm putting the jQuery tag as a beacon for all the web developers ninjas out there, but I don't really care about the framework (as long as its Javascript)
我把 jQuery 标签作为所有网络开发忍者的灯塔，但我并不真正关心框架（只要它的 Javascript）
回答by PeeHaa
Try using jQuery's focusand blurfunctions:
$(window).focus(function() {
console.log('welcome (back)');
});
$(window).blur(function() {
console.log('bye bye');
});<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
Click in and out of this frame to test the focus and blur functions.回答by jAndy
Use focusin(focus) and focusout(blur) on the documentobject:
在对象上使用focusin(focus) 和focusout(blur) document：
$(document).bind('focus', function() {
console.log('welcome (back)');
}).bind('blur', function() {
console.log('bye bye');
});
回答by Juan Mendes
I tested in FF and document.onfocusis called when I switch to that window.
我在 FF 中进行了测试，并document.onfocus在切换到该窗口时被调用。
