js判断当前浏览器窗口是否为可见状态

//检测当前窗口是否隐藏状态
function getHiddenProp()
{
var prefixes = ['webkit','moz','ms','o'];

// if 'hidden' is natively supported just return it
if ('hidden' in document) return 'hidden';

// otherwise loop over all the known prefixes until we find one
for (var i = 0; i < prefixes.length; i++)
{
if ((prefixes[i] + 'Hidden') in document)
return prefixes[i] + 'Hidden';
}

// otherwise it's not supported
return null;
}
//检测当前窗口是不是显示状态
function getVisibilityState()
{
var prefixes = ['webkit', 'moz', 'ms', 'o'];
if ('visibilityState' in document) return 'visibilityState';
for (var i = 0; i < prefixes.length; i++)
{
if ((prefixes[i] + 'VisibilityState') in document)
return prefixes[i] + 'VisibilityState';
}
// otherwise it's not supported
return null;
}

//查看当前窗口的状态（显示在标题标签上）
var visProp = getHiddenProp();
if (visProp)
{
var evtname = visProp.replace(/[H|h]idden/, '') + 'visibilitychange';
addEvent(document,evtname, function ()
{
// console.log(visProp)
document.title = document[getVisibilityState()]+"状态";
}, false);
}