window.open居中展示的代码写法

//咨询函数
function openswt() {
    window.open('https://webservice.zoosnet.net/LR/Chatpre.aspx?id=666&p=' + encodeURIComponent(window.location.href), 'newwindow', 'height=650,width=680,top=' + (screen.height - 650) / 2 + ',left=' + (screen.width - 680) / 2 + ',toolbar=no,menubar=no,scrollbars=no, resizable=no,location=no, status=no');
}