freeCodeCamp Challenge Guide: Counting Cards - Guide - The freeCodeCamp Forum

let count = 0;

function cc(card) {
  // Only change code below this line
  switch (card) {
    case 2:
    case 3:
    case 4:
    case 5:
    case 6:
      count++;
      break;
    case 10:
    case "J":
    case "Q":
    case "K":
    case "A":
      count--;
      break;
  }
  if (count > 0) {
    return count + " Bet";
  } else {
    return count + " Hold";
  }
  // Only change code above this line
}

cc(2); cc(3); cc(7); cc('K'); cc('A');
Code Explanation
Check the value of each card via a switch statement.
The variable count:
Increases by 1 if the card is a 2, 3, 4, 5, or 6.
Since 7, 8, and 9 aren’t worth anything, we ignore those cards in our switch statement.
Decreases by 1 if the card is a 10, ‘J’, ‘Q’, ‘K’, or ‘A’.
Check the value of count and return the appropriate response.
Example Run

cc(2); runs.
The switch statement hits case 2, jumps down and adds 1 to the variable count.
The switch statement then hits the break and cc(3); runs.
This cycle continues until the final call is made, cc('A');.
After the switch statement, the if statement checks count, which is now 0.
This then drops down to the else statement, which will return 0 Hold.
Note: As mentioned earlier, the switch statement could have also been an else if statement.