historify.js (yes, it's literate code!) is a simple set of functions that facilitate history management for single page applications (SPAs).
The main purpose of historify is to allow applications to have a "back" button, but make sure everything works seamlessly whether the user presses the browser's back button, or the app's back button.
This normally has challenges, as Javascript doesn't have access to the browser's history. So, it's necessary to keep a local copy of the browser's history and make sure that it's in sync with the browser's.