谁能修改下面javascript代码

Question

var Base64 = (function(undefined) {
            var Base64 = {},
            decoder;
            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
                    }
                }
                var out = [];
                var bits = 0,
                char_count = 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[out.length] = (bits >> 16);
                        out[out.length] = (bits >> 8) & 255;
                        out[out.length] = bits & 255;
                        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[out.length] = (bits >> 10);
                    break;
                case 3:
                    out[out.length] = (bits >> 16);
                    out[out.length] = (bits >> 8) & 255;
                    break
                }
                return out
            };
            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)
            };
            return Base64
        })(); 调用上面函数的是var der = Base64.unarmor(pem);