base64.js

// Base64 JavaScript decoder
// Copyright (c) 2008-2019 Lapo Luchini <lapo@lapo.it>

// Permission to use, copy, modify, and/or distribute this software for any
// purpose with or without fee is hereby granted, provided that the above
// copyright notice and this permission notice appear in all copies.
// 
// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
// WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
// MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
// ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
// WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
// ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
// OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

(function (undefined) {
"use strict";

var Base64 = {},
    decoder, // populated on first usage
    haveU8 = ('Uint8Array' in (typeof window == 'object' ? window : global));

Base64.decode = function (a) {
    var i;
    if (decoder === undefined) {
        var b64 = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/",
            ignore = "= \f\n\r\t\u00A0\u2028\u2029";
        decoder = [];
        for (i = 0; i < 64; ++i)
            decoder[b64.charAt(i)] = i;
        for (i = 0; i < ignore.length; ++i)
            decoder[ignore.charAt(i)] = -1;
        // RFC 3548 URL & file safe encoding
        decoder['-'] = decoder['+'];
        decoder['_'] = decoder['/'];
    }
    var out = haveU8 ? new Uint8Array(a.length * 3 >> 2) : [];
    var bits = 0, char_count = 0, len = 0;
    for (i = 0; i < a.length; ++i) {
        var c = a.charAt(i);
        if (c == '=')
            break;
        c = decoder[c];
        if (c == -1)
            continue;
        if (c === undefined)
            throw 'Illegal character at offset ' + i;
        bits |= c;
        if (++char_count >= 4) {
            out[len++] = (bits >> 16);
            out[len++] = (bits >> 8) & 0xFF;
            out[len++] = bits & 0xFF;
            bits = 0;
            char_count = 0;
        } else {
            bits <<= 6;
        }
    }
    switch (char_count) {
    case 1:
        throw "Base64 encoding incomplete: at least 2 bits missing";
    case 2:
        out[len++] = (bits >> 10);
        break;
    case 3:
        out[len++] = (bits >> 16);
        out[len++] = (bits >> 8) & 0xFF;
        break;
    }
    if (haveU8 && out.length > len) // in case it was originally longer because of ignored characters
        out = out.subarray(0, len);
    return out;
};

Base64.pretty = function (str) {
    // fix padding
    if (str.length % 4 > 0)
        str = (str + '===').slice(0, str.length + str.length % 4);
    // convert RFC 3548 to standard Base64
    str = str.replace(/-/g, '+').replace(/_/g, '/');
    // 80 column width
    return str.replace(/(.{80})/g, '$1\n');
};

Base64.re = /-----BEGIN [^-]+-----([A-Za-z0-9+\/=\s]+)-----END [^-]+-----|begin-base64[^\n]+\n([A-Za-z0-9+\/=\s]+)====/;
Base64.unarmor = function (a) {
    var m = Base64.re.exec(a);
    if (m) {
        if (m[1])
            a = m[1];
        else if (m[2])
            a = m[2];
        else
            throw "RegExp out of sync";
    }
    return Base64.decode(a);
};

// export globals
if (typeof module !== 'undefined') { module.exports = Base64; } else { window.Base64 = Base64; }
})();