在我身边，使用Chrome导航器，我必须使用DataView()来读取arrayBuffer

function _arrayBufferToBase64( tabU8A ) {
var binary = '';
let lecteur_de_donnees = new DataView(tabU8A);
var len = lecteur_de_donnees.byteLength;
var chaine = '';
var pos1;
for (var i = 0; i < len; i++) {
    binary += String.fromCharCode( lecteur_de_donnees.getUint8( i ) );
}
chaine = window.btoa( binary )
return chaine;}

我用了这个，对我很有用。

function arrayBufferToBase64( buffer ) {
    var binary = '';
    var bytes = new Uint8Array( buffer );
    var len = bytes.byteLength;
    for (var i = 0; i < len; i++) {
        binary += String.fromCharCode( bytes[ i ] );
    }
    return window.btoa( binary );
}



function base64ToArrayBuffer(base64) {
    var binary_string =  window.atob(base64);
    var len = binary_string.length;
    var bytes = new Uint8Array( len );
    for (var i = 0; i < len; i++)        {
        bytes[i] = binary_string.charCodeAt(i);
    }
    return bytes.buffer;
}

我使用TextDecode api将其转换为普通文本，然后将其转换为Base64

const uint =  new Uint8Array([ 73, 32, 108, 111, 118, 101, 32, 121, 111, 117 ]).buffer
const decoder = new TextDecoder()
const decodedText = decoder.decode(uint)
const base64Code = btoa(decodedText)

function _arrayBufferToBase64( buffer ) {
    var binary = '';
    var bytes = new Uint8Array( buffer );
    var len = bytes.byteLength;
    for (var i = 0; i < len; i++) {
        binary += String.fromCharCode( bytes[ i ] );
    }
    return window.btoa( binary );
}

但是，非本机实现更快，例如https://gist.github.com/958841 参见http://jsperf.com/encoding-xhr-image-data/6

更新的基准测试:https://jsben.ch/wnaZC

下面是两个简单的函数，用于将Uint8Array转换为Base64 String

arrayToBase64String(a) {
    return btoa(String.fromCharCode(...a));
}

base64StringToArray(s) {
    let asciiString = atob(s);
    return new Uint8Array([...asciiString].map(char => char.charCodeAt(0)));
}

对于那些喜欢简短的人，这里有另一个使用数组的例子。减少不会导致堆栈溢出:

var base64 = btoa(
  new Uint8Array(arrayBuffer)
    .reduce((data, byte) => data + String.fromCharCode(byte), '')
);