iOS: TVML: Navigating between pages

NextPage.xml

<document>
    <alertTemplate>
        <description>This page has been pushed onto the navigation stack.</description>
    </alertTemplate>
</document>

PageNavigation.xml

<document>
    <alertTemplate>
        <title>Welcome to Page Navigation</title>
        <description>This app shows how to navigate between TVML pages.</description>
        <button onselect="getDocument('templates/NextPage.xml')">
            <text>Next page</text>
        </button>
    </alertTemplate>
</document>

TVMLLoadingTemplates.js

function loadingDoc() {
    var template = `
    <document>
        <loadingTemplate>
            <activityIndicator><text>Loading</text></activityIndicator>
        </loadingTemplate>
    </document>
    `;
    
    var templateParser = new DOMParser();
    var parsedTemplate = templateParser.parseFromString(template, "application/xml");
    navigationDocument.pushDocument(parsedTemplate);
}

App.onLaunch = function(options) {

    loadingDoc()
    
    var templateURL = "templates/PageNavigation.xml";
    
    getDocument(templateURL);
}