字节单位转换

用于字节大小的转换

bytesToSize(bytes) {
       if (bytes === 0) {
        return '0 B';
        }

        let k = 1024;

        let sizes = ['B','KB', 'MB', 'GB', 'TB', 'PB', 'EB', 'ZB', 'YB'];
        let i = Math.floor(Math.log(bytes) / Math.log(k));
        let num = (bytes / Math.pow(k, i)).toFixed(1) > Math.floor((bytes / Math.pow(k, i))) ?
            (bytes / Math.pow(k, i)).toFixed(1) : Math.floor((bytes / Math.pow(k, i)));
        return num + ' ' + sizes[i];
    }