js 字节转换为B,KB,GB等

function bytesToSize(bytes) {
   if (bytes === 0) return '0 B';
   let k = 1024,
   sizes = ['B', 'KB', 'MB', 'GB', 'TB', 'PB', 'EB', 'ZB', 'YB'],
   i = Math.floor(Math.log(bytes) / Math.log(k));
   return (bytes / Math.pow(k, i)). toFixed(2) + ' ' + sizes[i];
}