eratosthenes algorithm for prime numbers

eratosthenes.js

const eratosthenes = n => {
    const output = []
    const upperLimit = Math.sqrt(n)
    // new array with n values of true i.e. [true, true, true...]
    const array = Array(n).fill(true)

    // loop from 2 to square root of n
    for (let i = 2; i <= upperLimit; i++) {
      // if i has been marked false, skip
      if (array[i]) {
        console.log(`i = ${i}`)
        // for inner loop, mark all multiples of i as false
        for (let j = i * i; j < n; j += i) {
          console.log(`${j} is not a prime`)
          array[j] = false;
        }
      }
    }

    // loop through array and push all true values into output
    array.forEach((e, i) => {
      if (e) output.push(i)
    })
    // slice 0 and 1 because those are not prime
    return output.slice(2)
};

console.log(eratosthenes(10)) // [ 2, 3, 5, 7 ]
console.log(eratosthenes(50)) // [ 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47 ]