How to Implement Logout Functionality and BackButton Event functionality in Phonegap

I am working in phonegap mobile application I want to implement logout functionality in my mobile application.

$('#logoutButton').off("click").on("click", function () {
        $("#pass").val("");
        window.localStorage.clear(); 
        
      $.mobile.changePage("#login",null,true,true);        
    
    });

In case you want backbutton to exit an app in one page and in other to act as a real back button you should use this:

document.addEventListener("backbutton", onBackKeyDown, false);

function onBackKeyDown() {
    if($.mobile.activePage.is('#loginpage')){
                 navigator.app.exitApp(); // Exit app if current page is a login page
    }
    else {
        navigator.app.backHistory(); // Go back in history in any other case
    }
}

To remove/prevent a backbutton event use this:

document.addEventListener("backbutton", function(e){
    e.preventDefault();
}, false);