如何使用javascript打开两侧的弹出窗口

I am developing a chat application here i have kept general chat room here multi users can chat with each other but now i want one to one chat in my application, when logged user click on any user in the user list, one pop up window should be opened on the user computer and another pop up window should be opened in the remote users computer , how can i achieve this , any help will be appreciated...I am developing a chat application here i have