Back Behaviour

The Back/Return button is a mandatory button on the remote control to go back or close the app.

The app may handle the Back/Return key event. If it does handle the Back/Return key, the app MUST handle both VK_BACK and VK_BACK_SPACE to ensure compatibility between legacy and current devices. On the remote control, the key may be marked with "Back", "Return" or similar. The Back/Return key should provide the user with typical back navigation, and finally, an exit path via window.close(); to leave the app and return to the previous screen.

document.addEventListener('keydown',function (e) {
/* Handling keydown event */
case VK_BACK:
        if(e.keycode == VK_BACK || e.keycode == VK_BACK_SPACE) {
             //Add prevent Default if focus is not on input field 
             if(!isInputfieldFocused())  { 
                 e.preventDefault();
                 // Now add your code below to handle BACK key
             }
        }
}, true);

// To detect the focus is in input field or not use below code
function isInputfieldFocused() {
    var activeElement = document.activeElement;
    if (activeElement && (activeElement.tagName.toLowerCase() === 'input' )) {
        console.log("focus is in input field");
        return true;
    } else {
        console.log("focus is not in input field")
        return false;
    }
}

How to use BACK key:

1. In case of multi page application : The app should use the historical behavior like window.history.go(-1)

   Back Behavior >>

   window.history.go(-1)

   
   

   Clean Exit >>

   if (typeof SmartTvA_API!= "undefined") {

               SmartTvA_API.exit();

       } else {

               window.close();

       }

2. In case of single page application : The app should use the hierarchical behavior.
   

3. To Exit from app, use window.close() method .
   

Important Recomendation :

• When the back key is pressed at the top level of the application or on-screen exit button (optional) is pressed, the app should follow "Back navigation" section in the "Application Development and UI Guidelines".  The app may give a confirmation message when exiting the app.  The TV device is to navigate back to the source application that called the application, but there could be exceptions
  

• The app should close the full screen mode when the remote control Back key is pressed during full screen video playback.
  NOTE: in case the app consists of showing a full screen video playback only, this requirement is not applicable.

• When pressing the remote control back key repeatedly, it should eventually exit the app. The app may give a confirmation message when exiting the app.