On Facebook, we can not usually see chat history, unless you’re chatting with that particular friend. If we want to go back to the chat we must wait for the friend to come back online and open the chat, and then we find the conversation to the point where we had left.
But with a little code / hack javascript can trace the history of a chat.
First we need to get the ID of the user. We can find it at the top of the address bar, when we visit the contact page (through friends of the friend or through search engines)
Another method of finding the ID of the user is going to click on "See All" in the friends box on your page. By copying this link will notice the id.
Once you find the ID Javascipt copy and paste the code in the address bar of your browser and replace 1122334455 with lD’s
javascript:buddyList.itemOnClick(1122334455);
[via: makeuseof]
