Given a set of factors, find the smallest number where all the factors evenly divide into the number

smallest_multiple.js

console.time('test');
function smallestMultiple(num) {
  if (num === 1) {
    return 1;
  }

  // generate factors from 4 to num
  let factors = {};
  for (let i = 2; i <= num; i++) {
    // factorization
    const factorized = factorize(i);
    Object.entries(factorized).forEach((factor) => {
      if (!factors[factor[0]] || factor[1] > factors[factor[0]]) {
        factors[factor[0]] = factor[1];
      }
    });
  }

  // multiple all slimfactors to find smallest multiple
  return Object.entries(factors).reduce((p, c) => {
    return p * Math.pow(parseInt(c[0]), c[1]);
  }, 1);
}

function factorize(num) {
  let factors = {};
  for (let i = 2; i <= num; i++) {
    while (num % i === 0) {
      if (factors[i]) {
        factors[i]++;
      } else {
        factors[i] = 1;
      }

      num = num / i;
    }
  }

  factors[num] = 1;

  return factors;
}

console.log(smallestMultiple(20));
console.timeEnd('test');
module.exports = smallestMultiple;