function isRotation(s1, s2) {
return (s1.length === s2.length) && (s1 + s1).indexOf(s2) !== -1;
}
let s1 = "abbc";
let s2 = "cabb";
console.log(isRotation(s1, s2) ? "yes" : "no");
s1 = "abbc";
s2 = "bbac";
console.log(isRotation(s1, s2) ? "yes" : "no");
/*
run:
yes
no
*/