I published a block 'URIEncodingComponent' to encoding URI for http POST for UTF-8.
https://snap.berkeley.edu/snap/snap.html#present:Username=tichan&ProjectName=URIEncodeComponent
It may compatible encodeURIComponent on javascript.
It referers
https://chromium.googlesource.com/v8/v8/+/3.30.3/src/uri.js
and
ECMA-262 - 15.1.3.4
Surrogate characters in UTF-8 are not tested well.