fizzbuzz.js

fizzbuzz = function(number) {
  if (number % 15 === 0) {
    return 'FizzBuzz'; 
  }
  if (number % 3 === 0) {
    return 'Fizz'; 
  }
  if (number % 5 === 0) {
    return 'Buzz'; 
  }
  return number;
}

fizzbuzzApp = function(toNumber) {
  var result = "";
  for(var i=1;i<=toNumber;i++) {
    result += fizzbuzz(i);
    if(i < toNumber) {
      result += "\n";
    }
  }
  return result;
}

fizzbuzzTest.js

require('./fizzbuzz.js');

assert = require('assert');

assert.equal('Fizz',fizzbuzz(3));
assert.equal('Fizz',fizzbuzz(33));
assert.equal('Fizz',fizzbuzz(66));

assert.equal('Buzz',fizzbuzz(5));
assert.equal('Buzz',fizzbuzz(55));
assert.equal('Buzz',fizzbuzz(100));

assert.equal('FizzBuzz', fizzbuzz(15));
assert.equal('FizzBuzz', fizzbuzz(45));
assert.equal('FizzBuzz', fizzbuzz(75));

assert.equal(2, fizzbuzz(2));
assert.equal(98, fizzbuzz(98));
assert.equal(41, fizzbuzz(41));

assert.equal("1\n2\nFizz\n4\nBuzz\nFizz", fizzbuzzApp(6));
assert.equal("1\n2\nFizz\n4\nBuzz\nFizz\n7\n8\nFizz\nBuzz\n11\nFizz\n13\n14\nFizzBuzz\n16", fizzbuzzApp(16));
assert.equal("", fizzbuzzApp(0));
assert.equal("", fizzbuzzApp(-1));

console.log('All tests passed');