You changed some class names in the html, so you need to do that in the javascript too. .category-item data-category
const seasonsNodes = document.querySelectorAll(`.category-item`);
const seasonsElement = document.getElementById("seasons-filter");
// click event handler for seasons choices
seasonsElement.addEventListener("click", filterBySeason);
// User clicked on Winter, Spring, Summer or Fall
// set an attribute filter on flood warnings layer view
// to display the warnings issued in that season
function filterBySeason(event) {
console.log(document.querySelectorAll('.category-item'));
const selectedSeason = event.target.getAttribute("data-category");
floodLayerView.filter = {
where: "Category = '" + selectedSeason + "'"
};
}