Meattale,
window.addEventListener("DOMContentLoaded", function() {
[].forEach.call( document.querySelectorAll('.sel'), function(el) {
var inputs = el.querySelectorAll("input.wicartoptional"), img = el.querySelector(".im");
[].forEach.call(inputs,
function(input, i) {
if(input.checked) {
img.src = ["http://javascript.ru/forum/images/smilies/dance3.gif","http://javascript.ru/forum/images/smilies/victory.gif"][i];
}
input.addEventListener("change", function() {
img.src = ["http://javascript.ru/forum/images/smilies/dance3.gif","http://javascript.ru/forum/images/smilies/victory.gif"][i];
})
})
});
});