Windows 8.1 includes the new Back button control. The BackButton provides a way for you to add backward navigation to your app.
<button data-win-control="WinJS.UI.BackButton" >button>
You don't have to write any code. The BackButton automatically checks the navigation stack to determine whether the user can navigate backwards. If there is nothing to navigate back to, the button disables itself. When the user clicks the button or uses keyboard shortcuts (such as Alt+Left or the BrowserBack keys), it automatically calls the WinJS.Navigation.back function to navigate backwards.