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