JS Bin// source https://jsbin.com/qupawe

getPrimesUpTo.js

// display prime numbers up to n.

'use strict';

var isPrime = function isPrime(number) {

    if (number < 2) return false;
    var sqrt = Math.floor(Math.sqrt(number));

    for (var i = 2; i <= sqrt; i++) {
        if (number % i === 0) {
            return false;
        }
    }

    return true;
};

var getPrimeNumbersUpTo = function getPrimeNumbersUpTo(number) {
    var primes = [];
    var sqrt = Math.floor(Math.sqrt(number));

    for (var i = 0; i <= number; i++) {
        if (isPrime(i)) {
            primes.push(i);
        }
    }

    return primes.join(', ');
};

console.log(getPrimeNumbersUpTo(100));