arraybuffer.js

// This solve the problem!
// @author: Jon Leighton
// Originated in https://gist.github.com/jonleighton/958841
export default function arrayBufferDataUri(raw) {
    var base64 = ''
    var encodings = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/'

    var bytes = new Uint8Array(raw)
    var byteLength = bytes.byteLength
    var byteRemainder = byteLength % 3
    var mainLength = byteLength - byteRemainder

    var a, b, c, d
    var chunk

    // Main loop deals with bytes in chunks of 3
    for (var i = 0; i < mainLength; i = i + 3) {
        // Combine the three bytes into a single integer
        chunk = (bytes[i] << 16) | (bytes[i + 1] << 8) | bytes[i + 2]

        // Use bitmasks to extract 6-bit segments from the triplet
        a = (chunk & 16515072) >> 18 // 16515072 = (2^6 - 1) << 18
        b = (chunk & 258048) >> 12 // 258048   = (2^6 - 1) << 12
        c = (chunk & 4032) >> 6 // 4032     = (2^6 - 1) << 6
        d = chunk & 63 // 63       = 2^6 - 1
        // Convert the raw binary segments to the appropriate ASCII encoding
        base64 += encodings[a] + encodings[b] + encodings[c] + encodings[d]
    }

    // Deal with the remaining bytes and padding
    if (byteRemainder === 1) {
        chunk = bytes[mainLength]

        a = (chunk & 252) >> 2 // 252 = (2^6 - 1) << 2
        // Set the 4 least significant bits to zero
        b = (chunk & 3) << 4 // 3   = 2^2 - 1
        base64 += encodings[a] + encodings[b] + '=='
    } else if (byteRemainder === 2) {
        chunk = (bytes[mainLength] << 8) | bytes[mainLength + 1]

        a = (chunk & 16128) >> 8 // 16128 = (2^6 - 1) << 8
        b = (chunk & 1008) >> 4 // 1008  = (2^6 - 1) << 4
        // Set the 2 least significant bits to zero
        c = (chunk & 15) << 2 // 15    = 2^4 - 1
        base64 += encodings[a] + encodings[b] + encodings[c] + '='
    }

    return 'data:image/jpeg;base64,' + base64
}