通过document.hidden属性判断当前页面是否是激活状态

网页当前状态判断，若不处于当前窗口则不发请求

var interval_output = null;
function sendRequst() {
     interval_output = setInterval(function () {
        SetClock();
    }, 60000);
}
sendRequst();

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('页面激活')
        sendRequst();
   } else {
      //console.log('页面非激活');
       clearInterval(interval_output);
  }
}
document.addEventListener(visibilityChangeEvent, onVisibilityChange);