Euler7.js

Euler7.js

var sys = require('sys');

var Euler7 = function() {

    var isPrimeNumber = function(num) {
	//1 is NOT a prime number
	if(num == 1) return false;
	//2 is a prime number. 
	if(num == 2) return true;
	//Exit early for even numbers (except 2 which is the only equal prime number). 
	if((num % 2)==0) {
	    return false;
	}

	//There is no reason to check numbers above the square root of the number. The reason is that if a divisor above the square root exists, one below will as well.
	for(var i=2;i<=Math.sqrt(num);i++) {
	    if(isDivisor(num,i)) {
		return false;
	    }
	}
	//If no divisors was found the number must be a prime.
	return true;
    }

   var isDivisor = function(number, candidate) {
	//If a division has no remainder the candidate is a divisor of number.
	return ((number%candidate)==0);
  }

  var getResult = function(primeCountNumber) {
    internalPrimeCount = 0;
    result = 0;
    for(var i=1;i<40000000;i++) {
	if(isPrimeNumber(i)) {
	    internalPrimeCount++;
	    if(internalPrimeCount==primeCountNumber) {
		result = i;
		break;
	    }
	}
    }
    sys.puts('Result: ' + result);
  }

  getResult(10001);
};

new Euler7();