Punycode Encoder (IDN to ASCII) Convert internationalized domain names to Punycode (xn--) format.

The tool works by first separating ASCII and non-ASCII characters in the input string, using Unicode code points to identify the character set. It then uses a delta encoding algorithm, as specified in RFC 3492, to process the non-ASCII code points, representing integers in a generalized variable-length format. The `punycodeEncode` function takes an input string and applies this algorithm, utilizing the `charCodeAt` method to get the Unicode code point for each character.

The adaptive bias calculation is performed using the `adapt` function, which adjusts the bias based on the delta value, number of points, and whether it's the first time through the loop. The `encodeDigit` function maps integers to ASCII characters, adding 22 to the input digit and applying an additional offset if the digit is less than 26. The encoded digits are then appended to the output array, which stores the Punycode-encoded result.

In terms of data structures, the tool uses arrays to store the basic ASCII characters, code points, and output digits. It also utilizes JavaScript's built-in `String` methods, such as `fromCodePoint`, to convert Unicode code points back into a string. The React library is used for building the user interface, with the `useCallback` hook memoizing the `onProcess` function to prevent unnecessary re-renders. When processing domain names, the tool splits the input string at dots using the `split` method and applies Punycode encoding to each label independently, checking for Unicode characters using a regular expression (`/[^\x00-\x7F]/`).

The encoded labels are then joined back together with dots in between using the `join` method. The resulting Punycode-encoded string is prefixed with 'xn--' to identify it as a valid Punycode label. This implementation ensures that each domain label is handled correctly, whether it contains ASCII or non-ASCII characters, producing output that can be used directly with DNS servers.