Base85 / Ascii85 Decoder Decode Base85 (Ascii85) encoded strings back to plain text.

The base85 decoding process begins by cleaning the input string of delimiters and whitespace characters, specifically removing '<~' from the start and '~>' from the end if present. This is achieved through JavaScript's `trim()` and `slice()` methods. The cleaned data then undergoes replacement of all whitespace characters with an empty string using a regular expression (`\s/g`).

When encountering a 'z' character, it gets replaced by four zero bytes (0x00), which corresponds to the Ascii85 standard for representing zeros in encoded data. For other characters, the tool processes them in 5-character chunks, padding any partial groups at the end with 'u' characters as necessary. Each chunk is then converted from base-85 to a decimal value using the formula `value = (padded.charCodeAt(j) - 33)` for each character position `j`, where `charCodeAt` returns the ASCII code of the character and subtracting 33 adjusts it according to Ascii85's custom alphabet.

This calculated integer is then split into four bytes, which are stored in a byte array (`bytes`). The number of output bytes depends on the length of the input chunk before padding. If the original group had fewer than five characters (before padding), only that many corresponding bytes are added to the `bytes` array after shifting and masking with 0xff. Finally, these bytes are converted back into human-readable text using a `TextDecoder`, which is part of the Web API for handling character encoding in web applications.

The tool's use of React for building its user interface allows it to dynamically handle input changes through the `useCallback` hook from React. This setup enables efficient re-renders and avoids unnecessary recalculations by memoizing the decoding function (`onProcess`). The decoded text is then displayed within a `TextToolLayout`, which organizes both the input field for the encoded string and the output area where the decoded result appears, complete with labels and placeholders to guide user interaction.