h5监听任何 App 自带的返回键，以及安卓机里的物理返回键

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);