function exercises from http://www.w3resource.com/javascript-exercises/javascript-functions-exercises.php

functions

//7
function countVowels(string) {
  var letters = string.split('');
  var vowels = "aeiou";
  var vowelIndex;
  var vowel;
  var vowelCount = 0;
  var i = 0;

  while (i < vowels.length) {
    if (letters.includes(vowels[i]) === true) {
      // Is this:
      vowelIndex = letters.indexOf(vowels[i]);
      vowel = letters.splice(vowelIndex, 1);
      // Better than this:
      // vowel = letters.splice(letters.indexOf(vowels[i]), 1);
      vowelCount++;
    }
    else {
      i++;
    }
  }
  console.log(vowelCount);
}
countVowels("The quick brown fox");



// 8
function checkPrime(num) {
  var i = 3;

  if (num != 2 && num % 2 == 0 || num < 2) {
    return "not prime";
  }
  else {
    while (i < num) {
      if (num % i == 0) {
        return "not prime";
      }
      else {
        i += 2
      }
    }
  }
  return "prime";
}
console.log(checkPrime(1));
console.log(checkPrime(97));
console.log(checkPrime(49));
console.log(checkPrime(2));


// 12
// v1 Sum of proper positive divisors
function checkPerfectNumber(num) {
  var sum = 0;
  for (var i = 1; i < num; i++) {
    if (num % i == 0) {
      sum += i;
    }
  }
  if (sum == num && num != 0) {
    return "perfect";
  }
  else {
    return "not perfect";
  }
}

// v2 Half sum of all positive divisors
function checkPerfectNumber(num) {
  var i = 1;
  var check = 0;

  while (i <= num) {
    if (num % i == 0) {
      check += i;
    }
    i++;
  }
  if (check / 2 == num && num != 0) {
    return "perfect";
  }
  else {
    return "not perfect";
  }
}

console.log(checkPerfectNumber(0));
console.log(checkPerfectNumber(1));
console.log(checkPerfectNumber(6));
console.log(checkPerfectNumber(28));
console.log(checkPerfectNumber(496));
console.log(checkPerfectNumber(2389));
console.log(checkPerfectNumber(8128));



// 17
function countLetters(string) {
  var letters = string.split('');
  var i;
  var currentLetter;
  var letterCounts = {};

  while (letters.length > 0) {
    i = 0;
    currentLetter = letters[i];
    while (letters.includes(currentLetter)) {
      if (letterCounts[currentLetter] == undefined) {
        letterCounts[currentLetter] = 1;
      }
      else {
        letterCounts[currentLetter] += 1;
      }
      // letters.splice(i, 1); // Mistake
      letters.splice(letters.indexOf(currentLetter), 1); // fixed
    }
  }
  console.log(letterCounts);
}
countLetters("dcbcdbcdacdd");


// 24
function bubbleSort(numbers) {
  var i = 0;
  var j;
  var holdValue;

  while (i < numbers.length) {
    j = 0;
    while (j < numbers.length) {
      if (numbers[j] > numbers[j + 1]) {
        holdValue = numbers[j];
        numbers[j] = numbers[j + 1];
        numbers[j+1] = holdValue
      }
      j++;
    }
    i++;
  }
  console.log(numbers);
}
bubbleSort([27, 29, 31, 36, 2014, 2012, 11, 17, -0.1, 4, 2016, 1.99, 40, 120.96]);