How can I check whether a browser window/tab is focused?

I know the window.blur / focus solution.

Can't use it.

It is a small widget. It lives in an iframe, and because of this, this method is not working. And since the iframe is loaded from a different domain there is no way to reach the top level window object.

Here: http://www.actionscript.org/forums/showpost.php3?p=1078962&postcount=5

"With the recent new 10.3 player this should be much easier, since there are new events for this specific situation."

So, using a simple flash object, and maybe js callbacks this might be the solution, but w开发者_运维问答hat are theese events? Does anyone know?

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This doesn't really answer your question, but you might want to take a look at the Page Visibility API. (I've also built a simple demo.)

What are you trying to do when the window/tab gets focus?

Can window.postMessage help you? (See this post for discussion of backwards compatible alternatives.)

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This probably isn’t helpful in general, but new versions of Firefox and Chrome reduce the setInterval timing to a maximum of one poll per second in background tabs. You could probably rig up an increment checker that compares a variable incrementing in a setInterval loop against a start Date / end Date value.