webAPI

当前界面是否可见，离开标签页时触发
let hidden,visibilitychange;
        if(typeof document.hidden !== "undefined"){
            hidden = "hidden";
            visibilitychange = "visibilitychange"
        }else if(typeof document.webkitHidden !== "undefined"){
            hidden = "webkitHidden";
            visibilitychange = "webkitvisibilitychange"
        }else if(typeof document.msHidden !== "undefined"){
            hidden = "msHidden";
            visibilitychange = "msvisiblitychange"
        }
        document.addEventListener(visibilitychange, ()=> {
            if(document['hidden']){
                game.stop()
            }
        })