[Yaml-core] Best way to output astral characters

Hello!
I am working on a cross-platform/cross-language program that uses YAML, and some of our users have noticed that the way our JS YAML parser outputs astral characters is not always recognized in YAML parsers in other languages. What is the "offical" (and best) way to output astral characters such as emojis in a way that all spec-compliant parsers should support?
Thanks in advance,Caleb In Him... I am complete (Col 2:9-10), confident that God will complete the good work he started 
(Phil 1:6), God's temple (1 Cor 3:16), more than a conqueror (Romans 8:37), His child (Eph 1).