Why can I not view an updated count for a variable with console.log in Javascript?

Question

I currently have this code below, it is supposed to emulate a card counting system, in which different characters increment/decrement the count when passed. The code below runs successfully, but when I attempt console.log(cc(2,3,4,5,6); it returns 1 Bet, when I know the code runs 5 Bet, as those characters should increment the count, yet console.log does not return the accurate count, I assume this is due to scope? But I would like if someone could explain why count isn't accurately returned.

var count = 0;

function cc(card) {
  switch(card) {
    case 2:
    case 3:
    case 4:
    case 5:
    case 6:
      count += 1;
      break;
    case 7:
    case 8:
    case 9:
      count += 0;
      break;
    case 10:
    case 'J':
    case 'Q':
    case 'K':
    case 'A':
      count -= 1;
      break;
  }

  if (count > 0) {
    return count + " Bet";
  } 
  else {
    return count + " Hold";
  }

}


cc(2,3,4,5,6); \\ returns 5 Bet
console.log(cc(2,3,4,5,6)); \\ returns 2 Bet

You're trying to pass five parameters into a function that only takes one, so the rest are ignored. — John Montgomery, Apr 02 '20 at 19:47
Also, count is not a function level variable. Its value changes whenever you call cc. — LearningEveryday, Apr 02 '20 at 19:50
Actually, it *should* log "2 Bet" since you're running it twice and using a global variable, so your code must be different from what you shared here. — John Montgomery, Apr 02 '20 at 19:51
I went ahead and changed the params to take 5 inputs and passed in (2,3,4,5,6) to look for any changes but the output is still the same. — ah2140, Apr 02 '20 at 20:00

score 0 · Answer 1 · answered Apr 02 '20 at 20:01

var count = 0;
const bet = card => {
  switch (card) {
    case 2:
    case 3:
    case 4:
    case 5:
    case 6:
      count += 1;
      break;
    case 7:
    case 8:
    case 9:
      count += 0;
      break;
    case 10:
    case "J":
    case "Q":
    case "K":
    case "A":
      count -= 1;
      break;
  }
};
function cc(...moves) {
  moves.forEach(bet);
  if (count > 0) {
    return count + " Bet";
  } else {
    return count + " Hold";
  }
}

console.log(cc(2, 3, 4, 5, 6)); // returns 5 Bet
console.log(cc(2, 3, 4, 5, 6)); // returns 10 Bet

Alex Wayne · Answer 2 · 2020-04-02T20:09:08.743

You have two major problems.

First, your count need to start at zero every time you call cc(). Because you have declared count outside the function, its values is preserved between calls to cc(). By declaring it inside the function, it's initialized to zero before it starts counting the card values.

(Unless you want to continue to the previous count, in which case you should keep it declared outside the function)

Second, your function only accepts one argument. You need to make it accept a list of arguments. This can be done simply with the spread operator .... Then you need to loop through each card value and do the count.

function cc(...cards) { // accept a list of card values as arguments.
  let count = 0

  for (const card of cards) { // loop through all card values.
    switch (card) {
      case 2:
      case 3:
      case 4:
      case 5:
      case 6:
        count += 1
        break
      case 7:
      case 8:
      case 9:
        count += 0
        break
      case 10:
      case 'J':
      case 'Q':
      case 'K':
      case 'A':
        count -= 1
        break
    }
  }

  if (count > 0) {
    return `${count} Bet`
  }

  return `${count} Hold`
}

cc(2, 3, 4, 5, 6) // returns 5 Bet
console.log(cc(2, 3, 4, 5, 6)) // returns 5 Bet
console.log(cc(2, 3, 4, 5, 6)) // returns 5 Bet

I understand having to insert count within the function in order to preserve it's value, but why did you change var to let? — ah2140, Apr 02 '20 at 20:49
No reason specific to this question. `let` is preferred in modern javascript. See [this for more discussion](https://stackoverflow.com/questions/762011/whats-the-difference-between-using-let-and-var) — Alex Wayne, Apr 02 '20 at 20:51

score 0 · Answer 3 · answered Apr 02 '20 at 20:04

Use arguments or splat operator to get all arguments passed and then loop it:

function cc(...cards) {
  var count = 0;
  var card;

  for (var i = 0; i < cards.length; i++) {
    card = cards[i];
    switch (card) {
      case 2:
      case 3:
      case 4:
      case 5:
      case 6:
        count += 1;
        break;
      case 7:
      case 8:
      case 9:
        count += 0;
        break;
      case 10:
      case 'J':
      case 'Q':
      case 'K':
      case 'A':
        count -= 1;
        break;
    }
  }

  if (count > 0) {
    return count + " Bet";
  } else {
    return count + " Hold";
  }
}



cc(2, 3, 4, 5, 6); // returns 5 Bet
console.log(cc(2, 3, 4, 5, 6)); // returns 2 Bet

Why can I not view an updated count for a variable with console.log in Javascript?

3 Answers3