You can also refer to the Unicode routines of other small JS engines[1,2], those don’t use ICU either, although the implementations are mercilessly size-optimiz

You can also refer to the Unicode routines of other small JS engines[1,2], those don’t use ICU either, although the implementations are mercilessly size-optimized (to put it politely) and restricted to what the target JS version requires (e.g. Duktape does casemapping but no normalization). Still, Bellard’s in particular look like he had a small Unicode processing library lying around and just copied it into the tree, not like he was forced to write the absolute minimum to do a JS inteprerer, so they can even be compared with dedicated libraries like libgrapheme, libutf8proc or libutf. [1] https://github.com/bellard/quickjs/blob/master/libunicode.c https://github.com/bellard/quickjs/blob/master/libunicode.c [2] https://github.com/svaarala/duktape/blob/master/src-input/duk_unicode.h https://github.com/svaarala/duktape/blob/master/src-input/du...