BiggestPrime - JavascriptModule0

// Biggest Prime Number
// Description
// Write a program that finds all prime numbers in the range 1 ... N. Use the Sieve of Eratosthenes algorithm. The program should print the biggest prime number which is <= N.
// Input
// On the first line you will receive the number N
// Output
// Print the biggest prime number which is <= N
// Constraints
// 2 <= N <= 10 000 000
// Sample tests
// Input Output
// 13 13
// 126 113
// 26 23

const input = ['10000000'];
const print = this.print || console.log;
const gets = this.gets || ((arr, index) => () => arr[index++])(input, 0);
let numberToCheck = +gets();
function isPrime (n) {
  if (n === 1) {
    return false;
  } else if (n === 2) {
    return true;
  } else {
    for (let i = 2; i < n; i++) {
      if (n % i === 0) {
        return false;
      }
    }
    return true;
  }
}
while (isPrime(numberToCheck) === false) {
  numberToCheck--;
}
print(numberToCheck);