perf_test.js

const {performance } = require('perf_hooks');
const N = 1000;
const M = 100000;
const alphabet = 'abcdefghijklmnopqrstuvwxyz';
const getRandomNum = to => Math.floor(Math.random() * to);
const getRandIdx = () => getRandomNum(alphabet.length);

function makeStrings(len = 100) {
  let arr = Array(len);
  let arr2 = Array(len);
  let rotPoint = getRandomNum(len);
  
  for (let i = 0; i < len; ++i) {
    let char = alphabet[getRandIdx()];
    arr[i] = char;
    arr2[(i + rotPoint) % len] = char;
  }
  
  return [arr.join(''), arr2.join('')];
}

function isRotate(s1, s2) {
    if (s1.length !== s2.length) {
      return false;
    }
    
    return (s1 + s1).indexOf(s2) > -1;
  }
  
function isRotate2(s1, s2) {
    if (s1.length !== s2.length) {
        return false;
    }

    for (let i = 0; i < s2.length; ++i) {
        if (s1 === (s2.slice(i) + s2.slice(0, i))) {
            return true;
        }
    }

    return false;
}



let couples = Array(N);
for (let i = 0; i < N; ++i) {
  couples[i] = makeStrings(M)//getRandomNum(100) + 1);
}

const t0 = performance.now();

let result1 = Array(couples.length);

for (let i = 0; i < couples.length; ++i) {
  result1[i] = isRotate(couples[i][0], couples[i][1]);
}

const t1 = performance.now();
console.log(`isRotate: ${t1 - t0} milliseconds.`);

const t2 = performance.now();

let result2 = Array(couples.length);

for (let i = 0; i < couples.length; ++i) {
  result2[i] = isRotate2(couples[i][0], couples[i][1]);
}

const t3 = performance.now();
console.log(`isRotate2: ${t3 - t2} milliseconds.`);

console.log(
    couples.length,
    result1.length,
    result2.length,
    // couples.slice(0, 3),
    // result1.slice(0, 3),
    // result2.slice(0, 3)
)