由于您想要显示单击元素旁边的对话框，您应该推迟设置对话框的位置，直到该信息可用，即在您的事件处理程序中：

Since you want to show the dialog next to the clicked element, you should defer setting the dialog's position until that information becomes available, i.e. in your event handler:

$("#selector").dialog({
    draggable: false,
    width: 250,
    autoOpen: false
});

$(".openDialog").click(function(e) {
    $("#selector").dialog("option", "position", [e.pageX, e.pageY])
                  .dialog("open");
});