document.querySelectorAll('.' + target_class).forEach(function(element, index) {
element.custom_index = index;
});
var arr = [ 1, 2, 3, 4, 5 ],
target_class = 'lol';
document.querySelectorAll('.' + target_class).forEach((el, i) => el.i = i);
window.addEventListener('click', function(e) {
if (e.target.classList.contains( target_class )) {
console.log( arr[ e.target.i ] );
}
});
$( c ).submit();