Encoding first converts your text to UTF-8 bytes with the browser's TextEncoder, then prints each byte as two hexadecimal digits — so Chinese characters, emoji and any Unicode text produce correct, standard byte sequences. Pick a separator (none, space or comma) and upper or lower case to match the format your code expects.
Decoding is forgiving: whitespace, commas and 0x prefixes are stripped before parsing, and strict UTF-8 decoding reports invalid input instead of producing garbage. Everything runs locally in your browser — nothing is uploaded.