檔案大小format

function formatDataSize(kb) {
    if (kb == '')
        return "";
    kb = parseInt(kb);
    var mb = kb / 1024;
    if (mb >= 1)
        return formatFloat(mb, 2) + " MB";
    else
        return kb + " KB";
}

function formatFloat(num, pos) {
    var size = Math.pow(10, pos);
    return Math.round(num * size) / size;
}