如果表示的单位小于10 KB或更大，则此解决方案包括一个小数点和一个十分位数字

const units = ['bytes', 'KB', 'MB', 'GB', 'TB', 'PB', 'EB', 'ZB', 'YB'];
   
function niceBytes(x){

  let l = 0, n = parseInt(x, 10) || 0;

  while(n >= 1024 && ++l){
      n = n/1024;
  }
  
  return(n.toFixed(n < 10 && l > 0 ? 1 : 0) + ' ' + units[l]);
}

结果:

niceBytes(7)                   // 7 bytes
niceBytes(435)                 // 435 bytes
niceBytes(3398)                // 3.3 KB
niceBytes(490398)              // 479 KB
niceBytes(6544528)             // 6.2 MB
niceBytes(23483023)            // 22 MB
niceBytes(3984578493)          // 3.7 GB
niceBytes(30498505889)         // 28 GB
niceBytes(9485039485039445)    // 8.4 PB

我最初在一个文件上传项目中使用@ al冰岛jm的答案，但最近遇到了一个问题，一个文件是0.98kb，但读取为1.02mb。下面是我现在使用的更新代码。

function formatBytes(bytes){
  var kb = 1024;
  var ndx = Math.floor( Math.log(bytes) / Math.log(kb) );
  var fileSizeTypes = ["bytes", "kb", "mb", "gb", "tb", "pb", "eb", "zb", "yb"];

  return {
    size: +(bytes / kb / kb).toFixed(2),
    type: fileSizeTypes[ndx]
  };
}

在像这样添加文件之后，上面的函数将被调用

// In this case `file.size` equals `26060275` 
formatBytes(file.size);
// returns `{ size: 24.85, type: "mb" }`

当然，Windows读取的文件为24.8mb，但我对额外的精度很满意。

您可以使用filesizejs库。

当与字节相关时，有两种真实的方法来表示大小，它们是SI单位(10^3)或IEC单位(2^10)。也有JEDEC，但他们的方法是模糊的和令人困惑的。我注意到其他示例有错误，例如使用KB而不是KB来表示千字节，因此我决定编写一个函数，使用当前接受的度量单位的范围来解决这些情况。

在结尾有一个格式化的地方，这将使数字看起来更好一点(至少在我看来)，如果它不适合你的目的，请随意删除这个格式。

享受。

// pBytes: the size in bytes to be converted.
// pUnits: 'si'|'iec' si units means the order of magnitude is 10^3, iec uses 2^10

function prettyNumber(pBytes, pUnits) {
    // Handle some special cases
    if(pBytes == 0) return '0 Bytes';
    if(pBytes == 1) return '1 Byte';
    if(pBytes == -1) return '-1 Byte';

    var bytes = Math.abs(pBytes)
    if(pUnits && pUnits.toLowerCase() && pUnits.toLowerCase() == 'si') {
        // SI units use the Metric representation based on 10^3 as a order of magnitude
        var orderOfMagnitude = Math.pow(10, 3);
        var abbreviations = ['Bytes', 'kB', 'MB', 'GB', 'TB', 'PB', 'EB', 'ZB', 'YB'];
    } else {
        // IEC units use 2^10 as an order of magnitude
        var orderOfMagnitude = Math.pow(2, 10);
        var abbreviations = ['Bytes', 'KiB', 'MiB', 'GiB', 'TiB', 'PiB', 'EiB', 'ZiB', 'YiB'];
    }
    var i = Math.floor(Math.log(bytes) / Math.log(orderOfMagnitude));
    var result = (bytes / Math.pow(orderOfMagnitude, i));

    // This will get the sign right
    if(pBytes < 0) {
        result *= -1;
    }

    // This bit here is purely for show. it drops the percision on numbers greater than 100 before the units.
    // it also always shows the full number of bytes if bytes is the unit.
    if(result >= 99.995 || i==0) {
        return result.toFixed(0) + ' ' + abbreviations[i];
    } else {
        return result.toFixed(2) + ' ' + abbreviations[i];
    }
}

我只是想分享我的想法。我遇到了这个问题，所以我的解决方案是这样的。这将把低单位转换为高单位，反之亦然，只需提供参数toUnit和fromUnit

export function fileSizeConverter(size: number, fromUnit: string, toUnit: string ): number | string {
  const units: string[] = ['B', 'KB', 'MB', 'GB', 'TB'];
  const from = units.indexOf(fromUnit.toUpperCase());
  const to = units.indexOf(toUnit.toUpperCase());
  const BASE_SIZE = 1024;
  let result: number | string = 0;

  if (from < 0 || to < 0 ) { return result = 'Error: Incorrect units'; }

  result = from < to ? size / (BASE_SIZE ** to) : size * (BASE_SIZE ** from);

  return result.toFixed(2);
}

我从这里得到了灵感

@ al冰岛jm也给出了同样的答案，但以一种“更说教”的方式。谢谢!= D

function formatBytes(numBytes, decPlaces) {
    /* Adjust the number of bytes informed for the most appropriate metric according
    to its value.

    Args:
        numBytes (number): The number of bytes (integer);
        decPlaces (Optional[number])): The number of decimal places (integer). If
            it is "undefined" the value "2" will be adopted.

    Returns:
        string: The number adjusted together with the most appropriate metric. */

    if (numBytes === 0) {
        return "0 Bytes";
    }

    // NOTE: 1 KB is equal to 1024 Bytes. By Questor
    // [Ref(s).: https://en.wikipedia.org/wiki/Kilobyte ]
    var oneKByte = 1024;

    // NOTE: Treats if the "decPlaces" is "undefined". If it is "undefined" the value
    // "2" will be adopted. By Questor
    if (decPlaces === undefined || decPlaces === "") {
        decPlaces = 2;
    }

    var byteMtrcs = ["Bytes", "KB", "MB", "GB", "TB", "PB", "EB", "ZB", "YB"];
    // Byte Metrics

    // NOTE: Defines the factor for the number of bytes and the metric. By Questor
    var mtrcNumbFactor = Math.floor(Math.log(numBytes) / Math.log(oneKByte));
    // Metrics Number Factor

    return parseFloat((numBytes / Math.pow(oneKByte, mtrcNumbFactor)).
            toFixed(decPlaces)) + " " + byteMtrcs[mtrcNumbFactor];
}