The nuances of base64 encoding strings in JavaScript

https://web.dev/articles/base64-encoding

Encoding unicode strings to base64 in javascript is not easy, but it is possible.

I knew that Javascript used UTF-16 internally, but today I learned about:

• String.fromCodePoint() - convert a sequence of code points into a string
• TextEncoder - allows you to convert a sequence of code points into a UTF-8 byte sequence
• TextDecoder - convert a byte sequence to a stream of code points from a variety of text encodings
• String.isWellFormed() - a new-ish function to check whether a string has any lone surrogates (is invalid UTF-16 - see wtf-8)