if (index < arrValue.length - 1) elem.value = arrValue[++index];
arrValue.forEach( function(value, i) {
if (value === elem.value && i > 0) elem.value = arrValue[--i];
});
if (index < arrValue.length - 1)
if (value === elem.value && i > 0)
function addActiveClass() {
for (let i = 0; i < arguments.length; i++) {
if (!arguments[i].classList.contains('active')) arguments[i].classList.add('active');
}
}