js弹出窗口不被阻止（可控制窗口位置与大小)

function openwindow(url,windowname,width,height){
    var x = parseint(screen.width / 2.0) - (width / 2.0);
    var y = parseint(screen.height / 2.0) - (height / 2.0);
    var ismsie= (navigator.appname == "microsoft internet explorer");
    if (ismsie) {
     var p = "resizable=1,location=no,scrollbars=no,width=";
     p = p+width;
     p = p+",height=";
     p = p+height;
     p = p+",left=";
     p = p+x;
     p = p+",top=";
     p = p+y;
        retval = window.open(url, windowname, p);
    } else {
        var win = window.open(url, "zyiispopup", "top=" + y + ",left=" + x + ",scrollbars=" + scrollbars + ",dialog=yes,modal=yes,width=" + width + ",height=" + height + ",resizable=no" );
        eval("try { win.resizeto(width, height); } catch(e) { }");
        win.focus();
    }

}
function client(o){
 
       var b = navigator.useragent.tolowercase();  
    var t = false;
    if (o == 'isop'){
    t = b.indexof('opera') > -1;
    }
    if (o == 'isie'){
    t = b.indexof('msie') > -1;
    }
    if (o == 'isff'){
    t = b.indexof('firefox') > -1;
    }
       return t;
};