function showImage() {
    var items = document.getElementsByClassName("item");
    for (var i = 0; i < items.length; i++) {
        items[i].addEventListener("change", func);
    }
}

function func(event) {
    var row = event.target.parentNode.parentNode;
    var itemValue = row.querySelector(".item").value;
    var itemNum = itemList.indexOf(itemValue);
    if (itemNum == 0) {
        row.querySelector(".image").innerHTML = "";
    } else {
        row.querySelector(".image").innerHTML =
                '<img alt="" class="img-rounded" width="150" src="static/' + (itemNum - 1) + '.jpg">';
    }
}

<img alt="" class="img-rounded" width="150" src="static/4.jpg">