AR Script epoch to readable date/time

var epoch = new Date(0);
epoch.setUTCSeconds(item.newBasename);

var day = zpad(epoch.getDate().toString(), 2); //day of the month
var month = zpad(epoch.getMonth().toString(), 2);
var year = epoch.getFullYear().toString();
var hour = zpad(epoch.getHours().toString(), 2);
var min = zpad(epoch.getMinutes().toString(), 2);
var sec = zpad(epoch.getSeconds().toString(), 2);

return year + "-" + month + "-" + day + "_" + hour + "-" + min + "-" + sec;

function zpad(str, nb_digits)
{
    if (str.length < nb_digits)
        { return (Array(nb_digits - str.length + 1).join('0') + str); }
    else
        { return str; }
}