我使用这个函数将文件大小(以字节为单位)转换为人类可读的文件大小:

零二线函数 var i = -1; var byteUnits =[英国‘计划生育’‘兆’,‘和合’,‘PB’‘EB”、“ZB’,‘YB]; do { fileSizeInBytes /= 1024; 我+; while (fileSizeInBytes > 1024) 数学归来。max(fileSizeInBytes, 0.1)。toFixed(1) + byteUnits[i]; 的 控制台日志(getReadableFileSizeString (1551859712);//输出是“1.4 GB”

然而,这似乎不是百分之百准确的。例如:

getReadableFileSizeString(1551859712); // output is "1.4 GB"

不应该是“1.5 GB”吗?除以1024似乎失去了精度。是我完全误解了什么,还是有更好的办法?


当前回答

我只是晚了10年!对于es6

function humanReadableSize(bytes) {
    let size = parseInt(data)
    for (let unit of ['b', 'Kb', 'Mb', 'Gb']) {
        if (size < 1024) return `${size.toFixed(2)} ${unit}`
        size /= 1024.0
    }
}

其他回答

计算的另一个体现

function humanFileSize(size) {
    var i = size == 0 ? 0 : Math.floor(Math.log(size) / Math.log(1024));
    return (size / Math.pow(1024, i)).toFixed(2) * 1 + ' ' + ['B', 'kB', 'MB', 'GB', 'TB'][i];
}

我写了一个大小转换函数,它也接受人类可读的格式。

JS

const bitBase = 8; const suffixes = { bit: 'b', b: 'B', kb: 'KB', mb: 'MB', gb: 'GB', tb: 'TB', }; const multipliers = { bit: { toBitHr: 1, toB: 1 / bitBase, toKB: 1 / (bitBase * 1e3), toMB: 1 / (bitBase * 1e6), toGB: 1 / (bitBase * 1e9), toTB: 1 / (bitBase * 1e12), }, B: { toBit: bitBase, toBHr: 1, toKB: 1 / 1e3, toMB: 1 / 1e6, toGB: 1 / 1e9, toTB: 1 / 1e12, }, KB: { toBit: 1 / (bitBase * 1e3), toB: 1e3, toKBHr: 1, toMB: 1 / 1e3, toGB: 1 / 1e6, toTB: 1 / 1e9, }, MB: { toBit: bitBase * 1e6, toB: 1e6, toKB: 1e3, toMBHr: 1, toGB: 1 / 1e3, toTB: 1 / 1e6, }, GB: { toBit: bitBase * 1e9, toB: 1e9, toKB: 1e6, toMB: 1e3, toGBHr: 1, toTB: 1 / 1e3, }, TB: { toBit: bitBase * 1e12, toB: 1e12, toKB: 1e9, toMB: 1e6, toGB: 1e3, toTBHr: 1, }, }; const round = (num, decimalPlaces) => { const strNum = num.toString(); const isExp = strNum.includes('e'); if (isExp) { return Number(num.toPrecision(decimalPlaces + 1)); } return Number( `${Math.round(Number(`${num}e${decimalPlaces}`))}e${decimalPlaces * -1}`, ); }; function conv( value, hr, rnd, multiplier, suffix, ) { let val = value * multiplier; if ((value * multiplier) > Number.MAX_SAFE_INTEGER) { val = Number.MAX_SAFE_INTEGER; } if (val < Number.MIN_VALUE) val = 0; if ((rnd || rnd === 0) && val < Number.MAX_SAFE_INTEGER) { val = round(val, rnd); } if (hr) return `${val}${suffix}`; return val; } const MemConv = (function _() { return { bit(value) { return { toBitHr(opts = {}) { return conv( value, true, opts.round || false, multipliers.bit.toBitHr, suffixes.bit, ); }, toB(opts = {}) { return conv( value, opts.hr || false, opts.round || false, multipliers.bit.toB, suffixes.b, ); }, toKB(opts = {}) { return conv( value, opts.hr || false, opts.round || false, multipliers.bit.toKB, suffixes.kb, ); }, toMB(opts = {}) { return conv( value, opts.hr || false, opts.round || false, multipliers.bit.toMB, suffixes.mb, ); }, toGB(opts = {}) { return conv( value, opts.hr || false, opts.round || false, multipliers.bit.toGB, suffixes.gb, ); }, toTB(opts = {}) { return conv( value, opts.hr || false, opts.round || false, multipliers.bit.toTB, suffixes.tb, ); }, }; }, B(value) { return { toBit(opts = {}) { return conv( value, opts.hr || false, opts.round || false, multipliers.B.toBit, suffixes.bit, ); }, toBHr(opts = {}) { return conv( value, true, opts.round || false, multipliers.B.toBHr, suffixes.b, ); }, toKB(opts = {}) { return conv( value, opts.hr || false, opts.round || false, multipliers.B.toKB, suffixes.kb, ); }, toMB(opts = {}) { return conv( value, opts.hr || false, opts.round || false, multipliers.B.toMB, suffixes.mb, ); }, toGB(opts = {}) { return conv( value, opts.hr || false, opts.round || false, multipliers.B.toGB, suffixes.gb, ); }, toTB(opts = {}) { return conv( value, opts.hr || false, opts.round || false, multipliers.B.toTB, suffixes.tb, ); }, }; }, KB(value) { return { toBit(opts = {}) { return conv( value, opts.hr || false, opts.round || false, multipliers.KB.toBit, suffixes.bit, ); }, toB(opts = {}) { return conv( value, opts.hr || false, opts.round || false, multipliers.KB.toB, suffixes.b, ); }, toKBHr(opts = {}) { return conv( value, true, opts.round || false, multipliers.KB.toKBHr, suffixes.kb, ); }, toMB(opts = {}) { return conv( value, opts.hr || false, opts.round || false, multipliers.KB.toMB, suffixes.mb, ); }, toGB(opts = {}) { return conv( value, opts.hr || false, opts.round || false, multipliers.KB.toGB, suffixes.gb, ); }, toTB(opts = {}) { return conv( value, opts.hr || false, opts.round || false, multipliers.KB.toTB, suffixes.tb, ); }, }; }, MB(value) { return { toBit(opts = {}) { return conv( value, opts.hr || false, opts.round || false, multipliers.MB.toBit, suffixes.bit, ); }, toB(opts = {}) { return conv( value, opts.hr || false, opts.round || false, multipliers.MB.toB, suffixes.b, ); }, toKB(opts = {}) { return conv( value, opts.hr || false, opts.round || false, multipliers.MB.toKB, suffixes.kb, ); }, toMBHr(opts = {}) { return conv( value, true, opts.round || false, multipliers.MB.toMBHr, suffixes.mb, ); }, toGB(opts = {}) { return conv( value, opts.hr || false, opts.round || false, multipliers.MB.toGB, suffixes.gb, ); }, toTB(opts = {}) { return conv( value, opts.hr || false, opts.round || false, multipliers.MB.toTB, suffixes.tb, ); }, }; }, GB(value) { return { toBit(opts = {}) { return conv( value, opts.hr || false, opts.round || false, multipliers.GB.toBit, suffixes.bit, ); }, toB(opts = {}) { return conv( value, opts.hr || false, opts.round || false, multipliers.GB.toB, suffixes.b, ); }, toKB(opts = {}) { return conv( value, opts.hr || false, opts.round || false, multipliers.GB.toKB, suffixes.kb, ); }, toMB(opts = {}) { return conv( value, opts.hr || false, opts.round || false, multipliers.GB.toMB, suffixes.mb, ); }, toGBHr(opts = {}) { return conv( value, true, opts.round || false, multipliers.GB.toGBHr, suffixes.gb, ); }, toTB(opts = {}) { return conv( value, opts.hr || false, opts.round || false, multipliers.GB.toTB, suffixes.tb, ); }, }; }, TB(value) { return { toBit(opts = {}) { return conv( value, opts.hr || false, opts.round || false, multipliers.TB.toBit, suffixes.bit, ); }, toB(opts = {}) { return conv( value, opts.hr || false, opts.round || false, multipliers.TB.toB, suffixes.b, ); }, toKB(opts = {}) { return conv( value, opts.hr || false, opts.round || false, multipliers.TB.toKB, suffixes.kb, ); }, toMB(opts = {}) { return conv( value, opts.hr || false, opts.round || false, multipliers.TB.toMB, suffixes.mb, ); }, toGB(opts = {}) { return conv( value, opts.hr || false, opts.round || false, multipliers.TB.toGB, suffixes.gb, ); }, toTBHr(opts = {}) { return conv( value, true, opts.round || false, multipliers.TB.toTBHr, suffixes.tb, ); }, }; }, }; }()); const testCases = [1, 10, 150, 1000, 74839.67346]; const HRSuffixes = Object.values(suffixes); const roundDecimals = 2; const precision = Number(`0.${'0'.repeat(roundDecimals)}5`); const SCIENTIFIC_NOT_NUMBER_REGXP = /[-+]?[0-9]*.?[0-9]+([eE][-+]?[0-9]+)?/g; const SUFFIX_REGXP = /[a-z]+$/i; const CONVERSION_TO_REGXP = /(?<=to).*(?=hr+$)|(?<=to).*(?=hr+$)?/i; for (const conversionFrom of (Object.keys(MemConv))) { for (const tCase of testCases) { const convFunc = MemConv[conversionFrom](tCase); for (const [conversionToFn, f] of Object.entries(convFunc)) { const conversionTo = (conversionToFn.match(CONVERSION_TO_REGXP) || [conversionToFn])[0]; const result = f(); const humanReadable = f({ hr: true }); const rounded = f({ round: roundDecimals }); const roundedAndHumanReadable = f({ hr: true, round: roundDecimals }); console.log({ value: tCase, from: conversionFrom, to: conversionTo, result, humanReadable, rounded, roundedAndHumanReadable, }); } } }

TSVersion

test

import assert from 'assert';

function test() {
  const testCases = [1, 10, 150, 1000, 74839.67346];
  const HRSuffixes = Object.values(suffixes);
  const roundDecimals = 2;
  const precision = Number(`0.${'0'.repeat(roundDecimals)}5`);
  const SCIENTIFIC_NOT_NUMBER_REGXP = /[-+]?[0-9]*.?[0-9]+([eE][-+]?[0-9]+)?/g;
  const SUFFIX_REGXP = /[a-z]+$/i;
  const CONVERSION_TO_REGXP = /(?<=to).*(?=hr+$)|(?<=to).*(?=hr+$)?/i;

  for (const conversionFrom of (Object.keys(MemConv) as (keyof typeof MemConv)[])) {
    for (const tCase of testCases) {
      const convFunc = MemConv[conversionFrom](tCase);
      for (const [conversionToFn, f] of Object.entries(convFunc)) {
        const conversionTo = (conversionToFn.match(CONVERSION_TO_REGXP) || [conversionToFn])[0];
        const expectedSuffix = suffixes[conversionTo.toLowerCase() as keyof typeof suffixes];
        const multiplier = multipliers[conversionFrom][conversionToFn as keyof typeof multipliers[typeof conversionFrom]];
        const expectedResult = tCase * multiplier > Number.MAX_SAFE_INTEGER
            ? Number.MAX_SAFE_INTEGER
            : tCase * multiplier;

        const result = f();
        const humanReadable = f({ hr: true });
        const rounded = f({ round: roundDecimals });
        const roundedAndHumanReadable = f({ hr: true, round: roundDecimals });

        const resHrNumber = Number((humanReadable.match(SCIENTIFIC_NOT_NUMBER_REGXP) || [''])[0]);
        const resHrSuffix = (humanReadable.match(SUFFIX_REGXP) || [0])[0];
        const resRoundHrNumber = Number((roundedAndHumanReadable.match(SCIENTIFIC_NOT_NUMBER_REGXP) || [''])[0]);
        const resRoundHrSuffix = (roundedAndHumanReadable.match(SUFFIX_REGXP) || [0])[0];

        if (/hr$/i.test(conversionToFn)) {
          const resNumber = Number((humanReadable.match(SCIENTIFIC_NOT_NUMBER_REGXP) || [''])[0]);
          const resSuffix = (humanReadable.match(SUFFIX_REGXP) || [0])[0];
          assert(typeof result === 'string');
          assert(typeof resSuffix === 'string');
          assert(typeof resRoundHrNumber === 'number');
          assert(typeof rounded === 'string');
          assert(result === humanReadable);
          assert(resSuffix === expectedSuffix);
          assert(resNumber <= expectedResult + precision && resNumber >= expectedResult - precision);
        } else {
          assert(typeof result === 'number');
          assert(result === resHrNumber);
          assert(typeof rounded === 'number');
          assert(result <= expectedResult + precision && result >= expectedResult - precision);
        }

        console.log({
          value: tCase,
          from: conversionFrom,
          to: conversionToFn,
          result,
          humanReadable,
          rounded,
          roundedAndHumanReadable,
        });

        assert(typeof resHrSuffix === 'string');
        assert(typeof resHrNumber === 'number');
        assert(resHrSuffix === expectedSuffix);
        assert(resHrSuffix === resRoundHrSuffix);
        assert(HRSuffixes.includes(resHrSuffix));
      }
    }
  }
}
test();

使用

// GB to GB humanReadable
console.log(MemConv.GB(11.1942).toGBHr()); // 11.1942GB;
// GB to MB
console.log(MemConv.GB(11.1942).toMB());// 11194.2;
// MB to MB humanReadable
console.log(MemConv.MB(11.1942).toGB({ hr: true }));// 0.011194200000000001GB;
// MB to MB humanReadable with rounding
console.log(MemConv.MB(11.1942).toGB({ hr: true, round: 3 }));// 0.011GB;

Let bytes = 1024 * 10 * 10 * 10;

控制台日志(getReadableFileSizeString(字节)。

将返回1000.0Кб而不是1MB

下面是一个将数字转换为符合新的国际标准的可读字符串的原型。

There are two ways to represent big numbers: You could either display them in multiples of 1000 = 10 3 (base 10) or 1024 = 2 10 (base 2). If you divide by 1000, you probably use the SI prefix names, if you divide by 1024, you probably use the IEC prefix names. The problem starts with dividing by 1024. Many applications use the SI prefix names for it and some use the IEC prefix names. The current situation is a mess. If you see SI prefix names you do not know whether the number is divided by 1000 or 1024

https://wiki.ubuntu.com/UnitsPolicy

http://en.wikipedia.org/wiki/Template:Quantities_of_bytes

Object.defineProperty(Number.prototype,'fileSize',{value:function(a,b,c,d){
 return (a=a?[1e3,'k','B']:[1024,'K','iB'],b=Math,c=b.log,
 d=c(this)/c(a[0])|0,this/b.pow(a[0],d)).toFixed(2)
 +' '+(d?(a[1]+'MGTPEZY')[--d]+a[2]:'Bytes');
},writable:false,enumerable:false});

这个函数不包含循环,所以它可能比其他一些函数快。

用法:

IEC前缀

console.log((186457865).fileSize()); // default IEC (power 1024)
//177.82 MiB
//KiB,MiB,GiB,TiB,PiB,EiB,ZiB,YiB

如果prefix

console.log((186457865).fileSize(1)); //1,true for SI (power 1000)
//186.46 MB 
//kB,MB,GB,TB,PB,EB,ZB,YB

我将IEC设置为默认值,因为我总是使用二进制模式来计算文件的大小…使用1024的幂


如果你只想在一个简短的线性函数中使用其中一个:

SI

function fileSizeSI(a,b,c,d,e){
 return (b=Math,c=b.log,d=1e3,e=c(a)/c(d)|0,a/b.pow(d,e)).toFixed(2)
 +' '+(e?'kMGTPEZY'[--e]+'B':'Bytes')
}
//kB,MB,GB,TB,PB,EB,ZB,YB

IEC

function fileSizeIEC(a,b,c,d,e){
 return (b=Math,c=b.log,d=1024,e=c(a)/c(d)|0,a/b.pow(d,e)).toFixed(2)
 +' '+(e?'KMGTPEZY'[--e]+'iB':'Bytes')
}
//KiB,MiB,GiB,TiB,PiB,EiB,ZiB,YiB

用法:

console.log(fileSizeIEC(7412834521));

如果你有关于函数的问题尽管问

另一个类似的例子

function fileSize(b) {
    var u = 0, s=1024;
    while (b >= s || -b >= s) {
        b /= s;
        u++;
    }
    return (u ? b.toFixed(1) + ' ' : b) + ' KMGTPEZY'[u] + 'B';
}

它所衡量的性能比其他具有相似特性的算法好得可以忽略不计。