html5桌面通知 提示

<button id="button">有人想加你为好友</button>
<p id="text"></p>
;(function (){    if(window.Notification){        var btn = document.getElementById("button");        var txt = document.getElementById("text");        btn.onclick = function (){            if(Notification.permission == "granted"){                popNotice();            }else if(Notification.permission != "denied"){                Notification.requestPermission().then(function (permission){                    popNotice()                })            }        };        function popNotice(){            if(Notification.permission == "granted"){                var notification = new Notification("你好:",{                    body:"请问今晚有空吗",                    icon:"http://image.zhangxinxu.com/左边头像地址"                });                notification.onclick = function (){                    txt.innerHTML = new Date().toTimeString().split(" ")[0]+"收到信息";                    notification.close();                }            }        }    }else{        console.log("浏览器不支持Notification");    }})();

Notification.requestPermission()是个请求 ，让浏览器出现是否允许通知的提示 和 Notification.permission 一样 返回 "3"
个值 "granted" "default" "denied" 户允许通知, 用户目前还没有管, 用户嫌弃