Help i have a problem with switch

Tell us what’s happening:
why is it that i dont have to include cases 7,8,9 and how does the function know it should be 0 when one of these cards is chosen?

Your code so far

var count = 0;

function cc(card) {
 // Only change code below this line
 switch (card){
   case 2:
   case 3:
   case 4:
   case 5:
   case 6:
     count ++;
   case 7:
   case 8:
   case 9:
   count = 0;
   case 10:
   case 'J':
   case 'Q':
   case 'K':
   case 'A':
      count --;


var holdbet= 'Hold';
if (count > 0){
  holdbet= 'Bet'
 return count + " " + holdbet;

 // Only change code above this line

console.log(cc(2); cc(8); cc(7); cc('K'); cc('A'));

Your browser information:

User Agent is: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/81.0.4044.122 Safari/537.36.

Challenge: Counting Cards

Link to the challenge:

and also do i have to use a default incase a string like ‘P’ , or ‘E’ is entered?

Because it starts at 0

In other words, you should add zero case the 7, 8, 9 cases. You are setting the count to zero, which is different.