How can I detect whether a browser window is focused or not?

Question

My page should make notification sounds only when the window is in the background. I can track the window.onfocus and window.onblur events to notice when the focus state changes. However, I don't know whether the window will load focused or not, since it might load in a background tab, for instance.

How do I decide whether to play sounds or not before I get an onfocus / onblur event?

Answer 1

难道你不能假设它被加载模糊，然后在收到任何类型的事件（keydown / mousemove）后立即将状态更改为焦点？

Answer 2

The onfocus event should be triggered when the page is initially opened (in the foreground). At least it is in FF3/IE8.

So you could have sounds on initially, turn them off when onfocus is triggered, and turn them back on when onblur is triggered.