在JavaScript中将大小（以字节为单位）转换为KB，MB，GB的正确方法

时间：2013-04-09 11:20:46

标签： javascript byte converters

我通过PHP得到this code以字节为单位隐藏大小。

现在我想使用JavaScript将这些尺寸转换为人类可读尺寸。我试图将此代码转换为JavaScript，如下所示：

function formatSizeUnits(bytes){
  if      (bytes >= 1073741824) { bytes = (bytes / 1073741824).toFixed(2) + " GB"; }
  else if (bytes >= 1048576)    { bytes = (bytes / 1048576).toFixed(2) + " MB"; }
  else if (bytes >= 1024)       { bytes = (bytes / 1024).toFixed(2) + " KB"; }
  else if (bytes > 1)           { bytes = bytes + " bytes"; }
  else if (bytes == 1)          { bytes = bytes + " byte"; }
  else                          { bytes = "0 bytes"; }
  return bytes;
}

这是正确的做法吗？有更简单的方法吗？

21 个答案:

答案 0 :(得分：553)

由此：（source）

function bytesToSize(bytes) {
   var sizes = ['Bytes', 'KB', 'MB', 'GB', 'TB'];
   if (bytes == 0) return '0 Byte';
   var i = parseInt(Math.floor(Math.log(bytes) / Math.log(1024)));
   return Math.round(bytes / Math.pow(1024, i), 2) + ' ' + sizes[i];
};

注意：这是原始代码，请使用下面的固定版本。 Aliceljm 不再激活她复制的代码

现在，未修改的固定版本，以及ES6：（按社区）

function formatBytes(bytes, decimals = 2) {
    if (bytes === 0) return '0 Bytes';

    const k = 1024;
    const dm = decimals < 0 ? 0 : decimals;
    const sizes = ['Bytes', 'KB', 'MB', 'GB', 'TB', 'PB', 'EB', 'ZB', 'YB'];

    const i = Math.floor(Math.log(bytes) / Math.log(k));

    return parseFloat((bytes / Math.pow(k, i)).toFixed(dm)) + ' ' + sizes[i];
}

现在，修正版： （由Stackoverflow社区提供，+由JSCompress缩小） 

function formatBytes(a,b){if(0==a)return"0 Bytes";var c=1024,d=b||2,e=["Bytes","KB","MB","GB","TB","PB","EB","ZB","YB"],f=Math.floor(Math.log(a)/Math.log(c));return parseFloat((a/Math.pow(c,f)).toFixed(d))+" "+e[f]}

用法： 

// formatBytes(bytes,decimals)

formatBytes(1024);       // 1 KB
formatBytes('1024');     // 1 KB
formatBytes(1234);       // 1.21 KB
formatBytes(1234, 3);    // 1.205 KB

演示/来源： 

function formatBytes(bytes,decimals) {
   if(bytes == 0) return '0 Bytes';
   var k = 1024,
       dm = decimals <= 0 ? 0 : decimals || 2,
       sizes = ['Bytes', 'KB', 'MB', 'GB', 'TB', 'PB', 'EB', 'ZB', 'YB'],
       i = Math.floor(Math.log(bytes) / Math.log(k));
   return parseFloat((bytes / Math.pow(k, i)).toFixed(dm)) + ' ' + sizes[i];
}


// ** Demo code **
var p = document.querySelector('p'),
    input = document.querySelector('input');
    
function setText(v){
    p.innerHTML = formatBytes(v);
}
// bind 'input' event
input.addEventListener('input', function(){ 
    setText( this.value )
})
// set initial text
setText(input.value);
<input type="text" value="1000">
<p></p>

PS：根据需要更改k = 1000或sizes = ["..."]（位或字节）

答案 1 :(得分：36)

function formatBytes(bytes) {
    if(bytes < 1024) return bytes + " Bytes";
    else if(bytes < 1048576) return(bytes / 1024).toFixed(3) + " KB";
    else if(bytes < 1073741824) return(bytes / 1048576).toFixed(3) + " MB";
    else return(bytes / 1073741824).toFixed(3) + " GB";
};

答案 2 :(得分：22)

const units = ['bytes', 'KB', 'MB', 'GB', 'TB', 'PB', 'EB', 'ZB', 'YB'];

function niceBytes(x){

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

  if(n === 1) return '1 byte'

  while(n >= 1024 && ++l){
      n = n/1024;
  }
  //include a decimal point and a tenths-place digit if presenting 
  //less than ten of KB or greater units
  return(n.toFixed(n < 10 && l > 0 ? 1 : 0) + ' ' + units[l]);
}

结果：

niceBytes(1)                   // 1 byte
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

答案 3 :(得分：12)

当与字节相关时，有两种实际方法来表示大小，它们是SI单位（10 ^ 3）或IEC单位（2 ^ 10）。还有JEDEC，但他们的方法含糊不清，令人困惑。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范围来解决每个案例。

最后有一个格式化位会使数字看起来更好（至少在我看来）如果它不适合你的目的，可以随意删除它。

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];
    }
}

答案 4 :(得分：11)

这是一个单行：

val => ['Bytes','Kb','Mb','Gb','Tb'][Math.floor(Math.log2(val)/10)]

甚至：

val => 'BKMGT'[~~(Math.log2(val)/10)]

答案 5 :(得分：10)

您可以使用filesizejs库。

答案 6 :(得分：5)

使用按位运算将是更好的解决方案。试试这个

function formatSizeUnits(bytes)
{
    if ( ( bytes >> 30 ) & 0x3FF )
        bytes = ( bytes >>> 30 ) + '.' + ( bytes & (3*0x3FF )) + 'GB' ;
    else if ( ( bytes >> 20 ) & 0x3FF )
        bytes = ( bytes >>> 20 ) + '.' + ( bytes & (2*0x3FF ) ) + 'MB' ;
    else if ( ( bytes >> 10 ) & 0x3FF )
        bytes = ( bytes >>> 10 ) + '.' + ( bytes & (0x3FF ) ) + 'KB' ;
    else if ( ( bytes >> 1 ) & 0x3FF )
        bytes = ( bytes >>> 1 ) + 'Bytes' ;
    else
        bytes = bytes + 'Byte' ;
    return bytes ;
}

答案 7 :(得分：4)

根据Aliceljm的回答，我在小数点后删除了0：

function formatBytes(bytes, decimals) {
    if(bytes== 0)
    {
        return "0 Byte";
    }
    var k = 1024; //Or 1 kilo = 1000
    var sizes = ["Bytes", "KB", "MB", "GB", "TB", "PB"];
    var i = Math.floor(Math.log(bytes) / Math.log(k));
    return parseFloat((bytes / Math.pow(k, i)).toFixed(decimals)) + " " + sizes[i];
}

答案 8 :(得分：2)

我最初使用@Aliceljm的答案来处理我正在处理的文件上传项目，但最近遇到的问题是文件为0.98kb但被读为1.02mb。这是我正在使用的更新代码。

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]
  };
}

然后在添加文件之后调用上面的内容

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

当然，Windows将文件读取为24.8mb，但我的精确度更高。

答案 9 :(得分：2)

function bytesToSize(bytes) {
  var sizes = ['B', 'K', 'M', 'G', 'T', 'P'];
  for (var i = 0; i < sizes.length; i++) {
    if (bytes <= 1024) {
      return bytes + ' ' + sizes[i];
    } else {
      bytes = parseFloat(bytes / 1024).toFixed(2)
    }
  }
  return bytes + ' P';
}

console.log(bytesToSize(234));
console.log(bytesToSize(2043));
console.log(bytesToSize(20433242));
console.log(bytesToSize(2043324243));
console.log(bytesToSize(2043324268233));
console.log(bytesToSize(2043324268233343));

答案 10 :(得分：1)

此解决方案基于以前的解决方案，但同时考虑了度量和二进制单位：

function formatBytes(bytes, decimals, binaryUnits) {
    if(bytes == 0) {
        return '0 Bytes';
    }
    var unitMultiple = (binaryUnits) ? 1024 : 1000; 
    var unitNames = (unitMultiple === 1024) ? // 1000 bytes in 1 Kilobyte (KB) or 1024 bytes for the binary version (KiB)
        ['Bytes', 'KiB', 'MiB', 'GiB', 'TiB', 'PiB', 'EiB', 'ZiB', 'YiB']: 
        ['Bytes', 'KB', 'MB', 'GB', 'TB', 'PB', 'EB', 'ZB', 'YB'];
    var unitChanges = Math.floor(Math.log(bytes) / Math.log(unitMultiple));
    return parseFloat((bytes / Math.pow(unitMultiple, unitChanges)).toFixed(decimals || 0)) + ' ' + unitNames[unitChanges];
}

示例：

formatBytes(293489203947847, 1);    // 293.5 TB
formatBytes(1234, 0);   // 1 KB
formatBytes(4534634523453678343456, 2); // 4.53 ZB
formatBytes(4534634523453678343456, 2, true));  // 3.84 ZiB
formatBytes(4566744, 1);    // 4.6 MB
formatBytes(534, 0);    // 534 Bytes
formatBytes(273403407, 0);  // 273 MB

答案 11 :(得分：1)

我在这里更新@Aliceljm答案。由于小数位对1,2位数字很重要，因此我将小数点后第一位并保留第一个小数位。对于3位数字，我将单位舍入并忽略所有小数位。

getMultiplers : function(bytes){
    var unit = 1000 ;
    if (bytes < unit) return bytes ;
    var exp = Math.floor(Math.log(bytes) / Math.log(unit));
    var pre = "kMGTPE".charAt(exp-1);
    var result = bytes / Math.pow(unit, exp);
    if(result/100 < 1)
        return (Math.round( result * 10 ) / 10) +pre;
    else
        return Math.round(result) + pre;
}

答案 12 :(得分：0)

var SIZES = ['Bytes', 'KB', 'MB', 'GB', 'TB', 'PB', 'EB', 'ZB', 'YB'];

function formatBytes(bytes, decimals) {
  for(var i = 0, r = bytes, b = 1024; r > b; i++) r /= b;
  return `${parseFloat(r.toFixed(decimals))} ${SIZES[i]}`;
}

答案 13 :(得分：0)

这是向人类显示一个字节的方式：

function bytesToHuman(bytes, decimals = 2) {
  // https://en.wikipedia.org/wiki/Orders_of_magnitude_(data)
  const units = ["bytes", "KiB", "MiB", "GiB", "TiB", "PiB", "EiB"]; // etc

  let i = 0;
  let h = 0;

  let c = 1 / 1023; // change it to 1024 and see the diff

  for (; h < c && i < units.length; i++) {
    if ((h = Math.pow(1024, i) / bytes) >= c) {
      break;
    }
  }

  // remove toFixed and let `locale` controls formatting
  return (1 / h).toFixed(decimals).toLocaleString() + " " + units[i];
}

// test
for (let i = 0; i < 9; i++) {
  let val = i * Math.pow(10, i);
  console.log(val.toLocaleString() + " bytes is the same as " + bytesToHuman(val));

}

// let's fool around
console.log(bytesToHuman(1023));
console.log(bytesToHuman(1024));
console.log(bytesToHuman(1025));

答案 14 :(得分：0)

我只想分享我的意见。我有这个问题，所以我的解决办法是这样。这会将较低的单位转换为较高的单位，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here那里得到了主意

答案 15 :(得分：0)

function bytes2Size(byteVal){
    var units=["Bytes", "KB", "MB", "GB", "TB"];
    var kounter=0;
    var kb= 1024;
    var div=byteVal/1;
    while(div>=kb){
        kounter++;
        div= div/kb;
    }
    return div.toFixed(1) + " " + units[kounter];
}

答案 16 :(得分：0)

单行

const b2s=t=>{let e=Math.log2(t)/10|0;return(t/1024**(e=e<=0?0:e)).toFixed(3)+"BKMGP"[e]};

console.log(b2s(0));
console.log(b2s(123));
console.log(b2s(123123));
console.log(b2s(123123123));
console.log(b2s(123123123123));
console.log(b2s(123123123123123));

答案 17 :(得分：0)

来自@Aliceljm 的相同答案，但以“更具说教性”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];
}

答案 18 :(得分：0)

function getReadableByte(count, decimal=0, level=0) {
    let unitList = ["Bytes", "KB", "MB", "GB", "TB", "PT"];

    if(count >= 1024.0 && (level+1 < unitList.length)) {
        return getReadableByte(count/1024, decimal, ++level)
    }
    return `${decimal ? (count).toFixed(decimal) : Math.round(count)}${unitList[level]}`
}

console.log(getReadableByte(120, 2))

function getReadableByte(count, decimal=0, level=0) { let unitList = ["Bytes", "KB", "MB", "GB", "TB", "PT"];

if(count >= 1024.0 && (level+1 < unitList.length)) {
    return getReadableByte(count/1024, decimal, ++level)
}
return `${decimal ? (count).toFixed(decimal) : Math.round(count)}${unitList[level]}`

}

console.log(getReadableByte(120, 2))

答案 19 :(得分：0)

这对我有用。

bytesForHuman(bytes) {
    let units = ['B', 'KB', 'MB', 'GB', 'TB', 'PB']

    let i = 0
    
    for (i; bytes > 1024; i++) {
        bytes /= 1024;
    }

    return bytes.toFixed(1) + ' ' + units[i]
}

答案 20 :(得分：-4)

尝试这个简单的解决方法。

var files = $("#file").get(0).files;               
                var size = files[0].size;
                if (size >= 5000000) {
alert("File size is greater than or equal to 5 MB");
}
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