[Aetae]

var atrs = document.querySelector('.arts');
var arr = atrs.innerHTML.split(','), i = arr.length;
while(i--){
    var trim = arr[i].trim();
    arr[i] = arr[i].replace(trim, '<a href="' + trim.replace(/\s/g,'_') + '">' + trim + '</a>');
}
atrs.innerHTML = arr.join(',');