Correct way to convert size in bytes to KB, MB, GB in JavaScript

Question

I got this code to covert size in bytes via PHP.

Now I want to convert those sizes to human readable sizes using JavaScript. I tried to convert this code to JavaScript, which looks like this:

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;
}

Is this the correct way of doing this? Is there an easier way?

Answer 1

From this: (source)

---

Unminified and ES6'ed: (by the community)

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

    const k = 1024
    const dm = decimals < 0 ? 0 : decimals
    const sizes = ['Bytes', 'KiB', 'MiB', 'GiB', 'TiB', 'PiB', 'EiB', 'ZiB', 'YiB']

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

    return `${parseFloat((bytes / Math.pow(k, i)).toFixed(dm))} ${sizes[i]}`
}

// Demo code
document.body.innerHTML += `<input type="text" oninput="document.querySelector('p').innerHTML=formatBytes(this.value)" value="1000"><p>1000 Bytes</p>`

Minified version (by StackOverflow's community, minified by JSCompress)

function formatBytes(a,b=2){if(!+a)return"0 Bytes";const c=0>b?0:b,d=Math.floor(Math.log(a)/Math.log(1024));return`${parseFloat((a/Math.pow(1024,d)).toFixed(c))} ${["Bytes","KiB","MiB","GiB","TiB","PiB","EiB","ZiB","YiB"][d]}`}

Usage:

// formatBytes(bytes, decimals)

formatBytes(1024)       // 1 KiB
formatBytes('1024')     // 1 KiB
formatBytes(1234)       // 1.21 KiB
formatBytes(1234, 3)    // 1.205 KiB
formatBytes(0)          // 0 Bytes
formatBytes('0')        // 0 Bytes

PS : Change k = 1000 or sizes = ["..."] as you want (bits or bytes)