使用h5新特性，轻松监听任何App自带返回键

过判断用户浏览的是否为当前页，从而进行相关操作。

var hiddenProperty = 'hidden' in document ? 'hidden' :
'webkitHidden' in document ? 'webkitHidden' :
'mozHidden' in document ? 'mozHidden' :
null;
var visibilityChangeEvent = hiddenProperty.replace(/hidden/i, 'visibilitychange');
var onVisibilityChange = function(){
if (document[hiddenProperty]) {
console.log('页面非激活');
}else{
console.log('页面激活')
}
}
document.addEventListener(visibilityChangeEvent, onVisibilityChange);