availableRoutes() function to determine where we can go.

availRoutes.js

function availableRoutes() {
    var horizontalSlides = document.querySelectorAll(HORIZONTAL_SLIDES_SELECTOR);
    var verticalSlides = document.querySelectorAll(VERTICAL_SLIDES_SELECTOR);

    return {
        left: indexh > 0,
        right: indexh < horizontalSlides.length - 1,
        up: indexv > 0,
        down: indexv < verticalSlides.length - 1
    };
}