function clearDomainCookies(domain) {
    var cookies = document.cookie.split(";");

    for (var i = 0; i < cookies.length; i++) {
        var cookie = cookies[i];
        var eqPos = cookie.indexOf("=");
        var name = eqPos > -1 ? cookie.substr(0, eqPos) : cookie;
        document.cookie = name + "=; expires=Thu, 01 Jan 1970 00:00:00 UTC; domain=" + domain + "; path=/;";
    }
}

// 在页面关闭时调用清除Cookie函数
window.addEventListener("beforeunload", function() {
    clearDomainCookies("123.com");
});