监听浏览器各个标签间的切换

      document.addEventListener('visibilitychange',function(e){
            console.log(document.visibilityState);
            let state = document.visibilityState
            if(state == 'hidden'){
                console.log(document.visibilityState,'用户离开了');
            }
            if(state == 'visible'){
                console.log(document.visibilityState,'回来了');
            }
        })