Simple encode in PHP and decode in Javascipt

Question

I'm working on a simple and safe PHP string encoding (with unicode support) and decoding in Javascript.

atob javascript function do not support Unicode, then I want to implement something like https://stackoverflow.com/a/30106551/49114 (Solution with binary interoperability) but I don't know how to correspond toBinary javascript methods in PHP.

Would be great to transcode toBinary and fromBinary from Javascript to PHP as reference :)

Thanks.

References: Using Javascript's atob to decode base64 doesn't properly decode utf-8 strings