如何检测关闭和刷新浏览器选项卡？

Question

我知道当你关闭标签时以及刷新标签时会触发此代码。

window.onbeforeunload = closingCode;
    function closingCode(e) {
        var evtobj = window.event ? event : e;

        var callDateUTC = { callDateUTC: new Date().toUTCString() };

        if (evtobj == e) {
            //firefox
            if (!evtobj.clientY) {
                that._apiGateway
                    .post(that._apiGateway.ApiPaths.RefreshToken, callDateUTC)
                    .subscribe((loginResponse: LoginResponse) => {
                    });
            }
        }
        else {
            //IE
            if (evtobj.clientY < 0) {
                that._apiGateway
                    .post(that._apiGateway.ApiPaths.RefreshToken, callDateUTC)
                    .subscribe((loginResponse: LoginResponse) => {
                    });
            }
        }

        return null;
    }

但我想知道这两个事件中的哪一个被触发了......

if (tabWasRefreshed){
    //code
}
else if(tabWasClosed){
    //code
}