MAKE CODEGOLF JAVASCRIPT 2 FUNCTIONS ENCODER AND DECODER OF ABACABA SO INPUT OF  𖦸᪣ TO MAKE OUTPUT ᪣𖦸᪣ ᪣𖦸᪣

JavaScript
e=s=>s&&e(s.slice(1))+s[0]+e(s.slice(1))
d=t=>t&&t[(l=t.length-1)/2]+d(t.slice(0,l/2))