js编码解码 punyCode

; (function (w) {

    function IdnMapping() {


        /** Highest positive signed 32-bit float value */
        var maxInt = 2147483647, // aka. 0x7FFFFFFF or 2^31-1

            /** Bootstring parameters */
            base = 36,
            tMin = 1,
            tMax = 26,
            skew = 38,
            damp = 700,
            initialBias = 72,
            initialN = 128, // 0x80
            delimiter = '-', // '\x2D'

            /** Regular expressions */
            regexPunycode = /^xn--/,
            regexNonASCII = /[^\x20-\x7E]/, // unprintable ASCII chars + non-ASCII chars
            regexSeparators = /[\x2E\u3002\uFF0E\uFF61]/g, // RFC 3490 separators

            /** Error messages */
            errors = {
                'overflow': 'Overflow: input needs wider integers to process',
                'not-basic': 'Illegal input >= 0x80 (not a basic code point)',
                'invalid-input': 'Invalid input'
            },

            /** Convenience shortcuts */
            baseMinusTMin = base - tMin,
            floor = Math.floor,
            stringFromCharCode = String.fromCharCode,

            /** Temporary variable */
            key;

        /*--------------------------------------------------------------------------*/

        /**
         * A generic error utility function.
         * @private
         * @param {String} type The error type.
         * @returns {Error} Throws a `RangeError` with the applicable error message.
         */
        function error(type) {
            throw RangeError(errors[type]);
        }

        /**
         * A generic `Array#map` utility function.
         * @private
         * @param {Array} array The array to iterate over.
         * @param {Function} callback The function that gets called for every array
         * item.
         * @returns {Array} A new array of values returned by the callback function.
         */
        function map(array, fn) {
            var length = array.length;
            var result = [];
            while (length--) {
                result[length] = fn(array[length]);
            }
            return result;
        }

        /**
         * A simple `Array#map`-like wrapper to work with domain name strings or email
         * addresses.
         * @private
         * @param {String} domain The domain name or email address.
         * @param {Function} callback The function that gets called for every
         * character.
         * @returns {Array} A new string of characters returned by the callback
         * function.
         */
        function mapDomain(string, fn) {
            var parts = string.split('@');
            var result = '';
            if (parts.length > 1) {
                // In email addresses, only the domain name should be punycoded. Leave
                // the local part (i.e. everything up to `@`) intact.
                result = parts[0] + '@';
                string = parts[1];
            }
            // Avoid `split(regex)` for IE8 compatibility. See #17.
            string = string.replace(regexSeparators, '\x2E');
            var labels = string.split('.');
            var encoded = map(labels, fn).join('.');
            return result + encoded;
        }

        /**
         * Creates an array containing the numeric code points of each Unicode
         * character in the string. While JavaScript uses UCS-2 internally,
         * this function will convert a pair of surrogate halves (each of which
         * UCS-2 exposes as separate characters) into a single code point,
         * matching UTF-16.
         * @see `punycode.ucs2.encode`
         * @memberOf punycode.ucs2
         * @name decode
         * @param {String} string The Unicode input string (UCS-2).
         * @returns {Array} The new array of code points.
         */
        function ucs2decode(string) {
            var output = [],
                counter = 0,
                length = string.length,
                value,
                extra;
            while (counter < length) {
                value = string.charCodeAt(counter++);
                if (value >= 0xD800 && value <= 0xDBFF && counter < length) {
                    // high surrogate, and there is a next character
                    extra = string.charCodeAt(counter++);
                    if ((extra & 0xFC00) == 0xDC00) { // low surrogate
                        output.push(((value & 0x3FF) << 10) + (extra & 0x3FF) + 0x10000);
                    } else {
                        // unmatched surrogate; only append this code unit, in case the next
                        // code unit is the high surrogate of a surrogate pair
                        output.push(value);
                        counter--;
                    }
                } else {
                    output.push(value);
                }
            }
            return output;
        }

        /**
         * Creates a string based on an array of numeric code points.
         * @see `punycode.ucs2.decode`
         * @memberOf punycode.ucs2
         * @name encode
         * @param {Array} codePoints The array of numeric code points.
         * @returns {String} The new Unicode string (UCS-2).
         */
        function ucs2encode(array) {
            return map(array,
                function (value) {
                    var output = '';
                    if (value > 0xFFFF) {
                        value -= 0x10000;
                        output += stringFromCharCode(value >>> 10 & 0x3FF | 0xD800);
                        value = 0xDC00 | value & 0x3FF;
                    }
                    output += stringFromCharCode(value);
                    return output;
                }).join('');
        }

        /**
         * Converts a basic code point into a digit/integer.
         * @see `digitToBasic()`
         * @private
         * @param {Number} codePoint The basic numeric code point value.
         * @returns {Number} The numeric value of a basic code point (for use in
         * representing integers) in the range `0` to `base - 1`, or `base` if
         * the code point does not represent a value.
         */
        function basicToDigit(codePoint) {
            if (codePoint - 48 < 10) {
                return codePoint - 22;
            }
            if (codePoint - 65 < 26) {
                return codePoint - 65;
            }
            if (codePoint - 97 < 26) {
                return codePoint - 97;
            }
            return base;
        }

        /**
         * Converts a digit/integer into a basic code point.
         * @see `basicToDigit()`
         * @private
         * @param {Number} digit The numeric value of a basic code point.
         * @returns {Number} The basic code point whose value (when used for
         * representing integers) is `digit`, which needs to be in the range
         * `0` to `base - 1`. If `flag` is non-zero, the uppercase form is
         * used; else, the lowercase form is used. The behavior is undefined
         * if `flag` is non-zero and `digit` has no uppercase form.
         */
        function digitToBasic(digit, flag) {
            //  0..25 map to ASCII a..z or A..Z
            // 26..35 map to ASCII 0..9
            return digit + 22 + 75 * (digit < 26) - ((flag != 0) << 5);
        }

        /**
         * Bias adaptation function as per section 3.4 of RFC 3492.
         * http://tools.ietf.org/html/rfc3492#section-3.4
         * @private
         */
        function adapt(delta, numPoints, firstTime) {
            var k = 0;
            delta = firstTime ? floor(delta / damp) : delta >> 1;
            delta += floor(delta / numPoints);
            for (/* no initialization */; delta > baseMinusTMin * tMax >> 1; k += base) {
                delta = floor(delta / baseMinusTMin);
            }
            return floor(k + (baseMinusTMin + 1) * delta / (delta + skew));
        }

        /**
         * Converts a Punycode string of ASCII-only symbols to a string of Unicode
         * symbols.
         * @memberOf punycode
         * @param {String} input The Punycode string of ASCII-only symbols.
         * @returns {String} The resulting string of Unicode symbols.
         */
        function decode(input) {
            // Don't use UCS-2
            var output = [],
                inputLength = input.length,
                out,
                i = 0,
                n = initialN,
                bias = initialBias,
                basic,
                j,
                index,
                oldi,
                w,
                k,
                digit,
                t,
                /** Cached calculation results */
                baseMinusT;

            // Handle the basic code points: let `basic` be the number of input code
            // points before the last delimiter, or `0` if there is none, then copy
            // the first basic code points to the output.

            basic = input.lastIndexOf(delimiter);
            if (basic < 0) {
                basic = 0;
            }

            for (j = 0; j < basic; ++j) {
                // if it's not a basic code point
                if (input.charCodeAt(j) >= 0x80) {
                    error('not-basic');
                }
                output.push(input.charCodeAt(j));
            }

            // Main decoding loop: start just after the last delimiter if any basic code
            // points were copied; start at the beginning otherwise.

            for (index = basic > 0 ? basic + 1 : 0; index < inputLength; /* no final expression */) {

                // `index` is the index of the next character to be consumed.
                // Decode a generalized variable-length integer into `delta`,
                // which gets added to `i`. The overflow checking is easier
                // if we increase `i` as we go, then subtract off its starting
                // value at the end to obtain `delta`.
                for (oldi = i, w = 1, k = base; /* no condition */; k += base) {

                    if (index >= inputLength) {
                        error('invalid-input');
                    }

                    digit = basicToDigit(input.charCodeAt(index++));

                    if (digit >= base || digit > floor((maxInt - i) / w)) {
                        error('overflow');
                    }

                    i += digit * w;
                    t = k <= bias ? tMin : (k >= bias + tMax ? tMax : k - bias);

                    if (digit < t) {
                        break;
                    }

                    baseMinusT = base - t;
                    if (w > floor(maxInt / baseMinusT)) {
                        error('overflow');
                    }

                    w *= baseMinusT;

                }

                out = output.length + 1;
                bias = adapt(i - oldi, out, oldi == 0);

                // `i` was supposed to wrap around from `out` to `0`,
                // incrementing `n` each time, so we'll fix that now:
                if (floor(i / out) > maxInt - n) {
                    error('overflow');
                }

                n += floor(i / out);
                i %= out;

                // Insert `n` at position `i` of the output
                output.splice(i++, 0, n);

            }

            return ucs2encode(output);
        }

        /**
         * Converts a string of Unicode symbols (e.g. a domain name label) to a
         * Punycode string of ASCII-only symbols.
         * @memberOf punycode
         * @param {String} input The string of Unicode symbols.
         * @returns {String} The resulting Punycode string of ASCII-only symbols.
         */
        function encode(input) {
            var n,
                delta,
                handledCPCount,
                basicLength,
                bias,
                j,
                m,
                q,
                k,
                t,
                currentValue,
                output = [],
                /** `inputLength` will hold the number of code points in `input`. */
                inputLength,
                /** Cached calculation results */
                handledCPCountPlusOne,
                baseMinusT,
                qMinusT;

            // Convert the input in UCS-2 to Unicode
            input = ucs2decode(input);

            // Cache the length
            inputLength = input.length;

            // Initialize the state
            n = initialN;
            delta = 0;
            bias = initialBias;

            // Handle the basic code points
            for (j = 0; j < inputLength; ++j) {
                currentValue = input[j];
                if (currentValue < 0x80) {
                    output.push(stringFromCharCode(currentValue));
                }
            }

            handledCPCount = basicLength = output.length;

            // `handledCPCount` is the number of code points that have been handled;
            // `basicLength` is the number of basic code points.

            // Finish the basic string - if it is not empty - with a delimiter
            if (basicLength) {
                output.push(delimiter);
            }

            // Main encoding loop:
            while (handledCPCount < inputLength) {

                // All non-basic code points < n have been handled already. Find the next
                // larger one:
                for (m = maxInt, j = 0; j < inputLength; ++j) {
                    currentValue = input[j];
                    if (currentValue >= n && currentValue < m) {
                        m = currentValue;
                    }
                }

                // Increase `delta` enough to advance the decoder's <n,i> state to <m,0>,
                // but guard against overflow
                handledCPCountPlusOne = handledCPCount + 1;
                if (m - n > floor((maxInt - delta) / handledCPCountPlusOne)) {
                    error('overflow');
                }

                delta += (m - n) * handledCPCountPlusOne;
                n = m;

                for (j = 0; j < inputLength; ++j) {
                    currentValue = input[j];

                    if (currentValue < n && ++delta > maxInt) {
                        error('overflow');
                    }

                    if (currentValue == n) {
                        // Represent delta as a generalized variable-length integer
                        for (q = delta, k = base; /* no condition */; k += base) {
                            t = k <= bias ? tMin : (k >= bias + tMax ? tMax : k - bias);
                            if (q < t) {
                                break;
                            }
                            qMinusT = q - t;
                            baseMinusT = base - t;
                            output.push(
                                stringFromCharCode(digitToBasic(t + qMinusT % baseMinusT, 0))
                            );
                            q = floor(qMinusT / baseMinusT);
                        }

                        output.push(stringFromCharCode(digitToBasic(q, 0)));
                        bias = adapt(delta, handledCPCountPlusOne, handledCPCount == basicLength);
                        delta = 0;
                        ++handledCPCount;
                    }
                }

                ++delta;
                ++n;

            }
            return output.join('');
        }


        this.toUnicode = function (input) {
            return mapDomain(input,
                function (string) {
                    return regexPunycode.test(string)
                        ? decode(string.slice(4).toLowerCase())
                        : string;
                });
        }


        this.toASCII = function (input) {
            return mapDomain(input,
                function (string) {
                    return regexNonASCII.test(string)
                        ? 'xn--' + encode(string)
                        : string;
                });
        }


    }

    window.IdnMapping = IdnMapping;
})(window);

使用:

 <script>
        window.onload = function () {
            var idn = new IdnMapping();
　　　　　　　//toASCII
            var str = idn.toASCII("www.博客园.com");
            console.log(str);
　　　　　　　　
　　　　　　　//toUnicode
            var str1 = idn.toUnicode(str);
            console.log(str1);
        }
    </script>