JavaScript: The Definitive Guide, 6th Edition

Browsing History

The history property of the Window object refers to the History object for the window. The History object models the browsing history of a window as a list of documents and document states. The length property of the History object specifies the number of elements in the browsing history list, but for security reasons scripts are not allowed to access the stored URLs. (If they could, any scripts could snoop through your browsing history.)

The History object has back() and forward() methods that behave like the browser’s Back and Forward buttons do: they make the browser go backward or forward one step in its browsing history. A third method, go(), takes an integer argument and can skip any number of pages forward (for positive arguments) or backward (for negative arguments) in the history list:

history.go(-2);   // Go back 2, like clicking the Back button twice

If a window contains child windows (such as <iframe> elements—see Relationships Between Frames), the browsing histories of the child windows are chronologically interleaved with the history of the main window. This means that calling history.back() (for example) on the main window may cause one of the child windows to navigate back to a previously displayed document but leave the main window in its current state.

Modern web applications can dynamically alter their own content without loading a new document (see Chapters 15 and 18, for example). Applications that do this may want to allow the user to use the Back ...