JSFiddle - React, Tailwind, and code Playground

JavaScript

function base64ToArrayBuffer(base64) {
    var binaryString =  window.atob(base64);
    var binaryLen = binaryString.length;
    var bytes = new Uint8Array(binaryLen);
    for (var i = 0; i < binaryLen; i++)        {
        var ascii = binaryString.charCodeAt(i);
        bytes[i] = ascii;
    }
    console.log('a',bytes);
    return bytes;
}

var saveByteArray = (function () {
    var a = document.createElement("a");
    document.body.appendChild(a);
    a.style = "display: none";
    return function (data, name) {
    		console.log(data, name);
        var blob = new Blob(data, {type: "octet/stream"}),
            url = window.URL.createObjectURL(blob);
            console.log(url);
        a.href = url;
        a.download = 'test.zip';
        a.click();
        window.URL.revokeObjectURL(url);
    };
}());


var sampleBytes = base64ToArrayBuffer('');
saveByteArray([sampleBytes], 'black1x1.gif');