js的hex转base64

if (!window.atob) {
            var tableStr = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
            var table = tableStr.split("");

            window.atob = function (base64) {
                if (/(=[^=]+|={3,})$/.test(base64)) throw new Error("String contains an invalid character");
                base64 = base64.replace(/=/g, "");
                var n = base64.length & 3;
                if (n === 1) throw new Error("String contains an invalid character");
                for (var i = 0, j = 0, len = base64.length / 4, bin = []; i < len; ++i) {
                    var a = tableStr.indexOf(base64[j++] || "A"), b = tableStr.indexOf(base64[j++] || "A");
                    var c = tableStr.indexOf(base64[j++] || "A"), d = tableStr.indexOf(base64[j++] || "A");
                    if ((a | b | c | d) < 0) throw new Error("String contains an invalid character");
                    bin[bin.length] = ((a << 2) | (b >> 4)) & 255;
                    bin[bin.length] = ((b << 4) | (c >> 2)) & 255;
                    bin[bin.length] = ((c << 6) | d) & 255;
                };
                return String.fromCharCode.apply(null, bin).substr(0, bin.length + n - 4);
            };

            window.btoa = function (bin) {
                for (var i = 0, j = 0, len = bin.length / 3, base64 = []; i < len; ++i) {
                    var a = bin.charCodeAt(j++), b = bin.charCodeAt(j++), c = bin.charCodeAt(j++);
                    if ((a | b | c) > 255) throw new Error("String contains an invalid character");
                    base64[base64.length] = table[a >> 2] + table[((a << 4) & 63) | (b >> 4)] +
                        (isNaN(b) ? "=" : table[((b << 2) & 63) | (c >> 6)]) +
                        (isNaN(b + c) ? "=" : table[c & 63]);
                }
                return base64.join("");
            };

        }

        function hexToBase64(str) {
            return btoa(String.fromCharCode.apply(null,
                str.replace(/
|
/g, "").replace(/([da-fA-F]{2}) ?/g, "0x$1 ").replace(/ +$/, "").split(" "))
            );
        }

        function base64ToHex(str) {
            for (var i = 0, bin = atob(str.replace(/[ 
]+$/, "")), hex = []; i < bin.length; ++i) {
                var tmp = bin.charCodeAt(i).toString(16);
                if (tmp.length === 1) tmp = "0" + tmp;
                hex[hex.length] = tmp;
            }
            return hex.join(" ");
        }