updateTileImage.js

function updateTile(message, imgUrl, imgAlt) {
    // Namespace: Windows.UI.Notifications
    if (typeof Windows !== 'undefined'&&
            typeof Windows.UI !== 'undefined' &&
            typeof Windows.UI.Notifications !== 'undefined') {

        var notifications = Windows.UI.Notifications,
        tile = notifications.TileTemplateType.tileSquare150x150PeekImageAndText01,
        tileContent = notifications.TileUpdateManager.getTemplateContent(tile),
        tileText = tileContent.getElementsByTagName('text'),
        tileImage = tileContent.getElementsByTagName('image');

        tileText[0].appendChild(tileContent.createTextNode(message || 'Demo Message'));
        tileImage[0].setAttribute('src', imgUrl || 'https://unsplash.it/150/150/?random');
        tileImage[0].setAttribute('alt', imgAlt || 'Random demo image');

        var tileNotification = new notifications.TileNotification(tileContent);
        var currentTime = new Date();
        tileNotification.expirationTime = new Date(currentTime.getTime() + 600 * 1000);
        notifications.TileUpdateManager.createTileUpdaterForApplication().update(tileNotification);
    } else {
        //Alternative behavior
    }
}