Slide Index vs. Picture Index
https://stackoverflow.com/questions/47588415/calculate-picture-id-for-gallery-with-ads
by Patrick Hund
JavaScript
const numberOfSlides = 11;
const adInterval = 3; // display ad after x pictures
const logData = [['slide index', 'pic index']];
for (let slideIndex = 0; slideIndex < numberOfSlides; slideIndex++) {
const picIndex = slideIndex - Math.floor(slideIndex / adInterval);
logData.push([slideIndex, picIndex]);
}
console.table(logData);