How to handle back button of an UWP app with Javascript?

Question

I am building an UWP app with JavaScript. Currently clicking the Back Button closes the app. However, I want it to call a JavaScript function.

It'd be great if anyone can share the code for Creating a Windows Runtime component and calling it from JavaScript to handle the Back Button press.

Answer 1

var systemNavManager = Windows.UI.Core.SystemNavigationManager.getForCurrentView();

function startApp(){
    // backRequested event
    if (systemNavManager !== null) {
        systemNavManager.addEventListener("backrequested", backRequested, false);
    }
}

function backRequested() {
    if (window.location.href.indexOf("/default.html") === -1) {  // not on home page, go back
        // nav back
        window.history.back();
    }
}

Source: https://github.com/Microsoft/TVHelpers/blob/master/WinRTjs/BackBtnTitleBarCustomization/js/main.js