function humanReadableFilesize(size) {
        var units = new Array("B", "KB", "MB", "GB", "TB", "PB");
        var mod = 1024.0;
        var i = 0;
        while (size >= mod) {
            size /= mod;
            i++;
        }
        //return Math.round(size) + units[i];
        return formatNum(size, 1) + units[i];
    }

    //格式化数字类型,保留小数点后几位,非四舍五入
    //size:值
    //n:保留位数
    function formatNum(size, n) {
        var sizeStr = size.toString();
        if (sizeStr.lastIndexOf(‘.‘) > -1)
            return sizeStr.substring(0, sizeStr.toString().indexOf(‘.‘) + 1 + n);
        else
            return sizeStr;
    }