我得到这段代码通过PHP隐蔽大小字节。

现在我想使用JavaScript将这些大小转换为人类可读的大小。我尝试将这段代码转换为JavaScript,看起来像这样:

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?有没有更简单的方法?


当前回答

@ 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];
}

其他回答

试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");
}

我让算法快了7倍(就像忍者一样):

function rafaelFormatBytes(number){ if(number == null || number === undefined || number <= 0) { return '0 Bytes'; } var scaleCounter = 0; var scaleInitials = [' Bytes',' KB',' MB',' GB',' TB',' PB',' EB',' ZB',' YB']; while (number >= 1024 && scaleCounter < scaleInitials.length - 1){ number /= 1024; scaleCounter++; } if(scaleCounter >= scaleInitials.length) scaleCounter = scaleInitials.length - 1; var compactNumber = number.toFixed(2) .replace(/\.?0+$/,'') .replace(/\B(?=(\d{3})+(?!\d))/g, ","); compactNumber += scaleInitials[scaleCounter]; return compactNumber.trim(); } var testNum = 0; var startTime, endTime; function start() { startTime = new Date(); }; function end() { endTime = new Date(); var timeDiff = endTime - startTime; //in ms // strip the ms timeDiff /= 1000; // get seconds var seconds = Math.round(timeDiff, 5); console.log(timeDiff + " seconds"); } function formatBytes(a,b=2,k=1024){with(Math){let d=floor(log(a)/log(k));return 0==a?"0 Bytes":parseFloat((a/pow(k,d)).toFixed(max(0,b)))+" "+["Bytes","KB","MB","GB","TB","PB","EB","ZB","YB"][d]}} console.log(formatBytes(1000000000000000000000000000)); console.log(rafaelFormatBytes(1000000000000000000000000000)); start(); for(i=0; i<100000; i++){ formatBytes(1000000000000000); } end(); start(); for(i=0; i<100000; i++){ rafaelFormatBytes(1000000000000000); } end();

... 输出:

827.18 YB
827.18 YB
0.293 seconds
0.039 seconds

耶稣基督!

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

这是一个坚实的有效的方法来转换字节。你唯一需要做的就是安装mathjs库进行精确的计算。复制粘贴即可。

import { multiply, divide, round } from "mathjs";

class Size {
  constructor(value, unit) {
    this.value = value;
    this.unit = unit.toUpperCase();
  }
}

async function byteToSize(bytes) {
  const B = 1;
  const KB = multiply(B, 1024);
  const MB = multiply(KB, 1024);
  const GB = multiply(MB, 1024);
  const TB = multiply(GB, 1024);
  const PB = multiply(TB, 1024);

  if (bytes <= KB) {
    // @returns BYTE

    const result = round(divide(bytes, B));
    const unit = `B`;

    return new Size(result, unit);
  }

  if (bytes <= MB) {
    // @returns KILOBYTE

    const result = round(divide(bytes, KB));
    const unit = `KB`;

    return new Size(result, unit);
  }

  if (bytes <= GB) {
    // @returns MEGABYTE

    const result = round(divide(bytes, MB));
    const unit = `MB`;

    return new Size(result, unit);
  }

  if (bytes <= TB) {
    // @returns GIGABYTE

    const result = round(divide(bytes, GB));
    const unit = `GB`;

    return new Size(result, unit);
  }

  if (bytes <= PB) {
    // @returns TERABYTE

    const result = divide(bytes, TB).toFixed(2);
    const unit = `TB`;

    return new Size(result, unit);
  }

  if (bytes >= PB) {
    // @returns PETABYTE

    const result = divide(bytes, PB).toFixed(2);
    const unit = `PB`;

    return new Size(result, unit);
  }
}

你可以使用pretty-bytes库。

安装

npm install pretty-bytes

使用

import prettyBytes from 'pretty-bytes';

prettyBytes(1337);
//=> '1.34 kB'

prettyBytes(100);
//=> '100 B'

// Display with units of bits
prettyBytes(1337, {bits: true});
//=> '1.34 kbit'

// Display file size differences
prettyBytes(42, {signed: true});
//=> '+42 B'

// Localized output using German locale
prettyBytes(1337, {locale: 'de'});
//=> '1,34 kB'