Convert a TypedArray Buffer to Base64 in JavaScript

See also

• Unicode, UTF-8, TypeArray, Uint8Array, JavaScript, and You
• Direct Unicode to Uint8Array JavaScript conversion

This code was inspired by Unibabel JS, which in turn was inspired by MDN's The Unicode Problem.

If you need a pure "vanilla" JavaScript implementation which does not rely on the DOM or node.js, check out beatgammit's base64-js.

Note: You can get this to work all the way back to MSIE6 by replacing 'Uint8Array()' with 'Array()' and providing an Array polyfill for 'map' and 'forEach'.

from Uint8Array to Base64

'use strict';

function bufferToBase64(buf) {
    var binstr = Array.prototype.map.call(buf, function (ch) {
        return String.fromCharCode(ch);
    }).join('');
    return btoa(binstr);
}

Demo

          // "I ½ ♥ 💩";
var arr = [73, 32, 194, 189, 32, 226, 153, 165, 32, 240, 159, 146, 169];
var data = new Uint8Array(arr);

var base64 = bufferToBase64(data); // "SSDCvSDimaUg8J+SqQ=="

from Base64 to Uint8Array

'use strict';

function base64ToBuffer(base64) {
    var binstr = atob(base64);
    var buf = new Uint8Array(binstr.length);
    Array.prototype.forEach.call(binstr, function (ch, i) {
      buf[i] = ch.charCodeAt(0);
    });
    return buf;
}

Demo

var base64 = "SSDCvSDimaUg8J+SqQ==";

var buf = base64ToBuffer(base64);

var arr = Array.prototype.slice.call(buf);
// "I ½ ♥ 💩";
// [73, 32, 194, 189, 32, 226, 153, 165, 32, 240, 159, 146, 169]

This needs to be standardized!

Please contact your local JavaScript standardization committee to recommend that a feature be standardized in JavaScript.

Note: That atob and btoa are not even part of JavaScript, they are proprietary to the DOM.

By AJ ONeal


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