How to Get chat history even if friend is offline

A Facebook profile page shows up explaining the steps on how to get chat history of a friend on Facebook. It explains that you need to go to the profile of the person you would like to find chat history with. It then explains steps on how you can copy there Facebook ID. Once you have accessed that he provides you with a JavaScript code to use to pull up chat history. He gives you step by step examples explaining how to set up the ID and apply it to the JavaScript coding. Once that has been established you will then copy and paste the ID and coding into your browsers address bar and hit enter. Your Facebook chat box will appear on your screen with all the chat history of the person you choose, even if they are offline.