let jumbotron = document.querySelector('.jumbotron');
let topImageHolder = document.querySelector('.jumbotron-image[data-order="1"]');
let bottomImageHolder = document.querySelector('.jumbotron-image[data-order="2"]');
let images = jumbotron.getAttribute('data-images').split(',');
let delay = jumbotron.getAttribute('data-delay');
let imageIndex = 0;

// init
bottomImageHolder.src = images[imageIndex];
imageIndex++;

function loop() {
    bottomImageHolder.classList.add('op0');
    bottomImageHolder.src = images[imageIndex];
    imageIndex++;

    topImageHolder.classList.add('op0');
    topImageHolder.src = images[imageIndex];
    imageIndex++;

    bottomImageHolder.classList.remove('op0');
    if (imageIndex >= images.length) {
        imageIndex = 0;
    }
}

setInterval(loop, delay);