Build a Cash Register Project - Build a Cash Register

JavaScript
22

Ok, what line is supposed to add the text about the pennies

23

this line:

const formattedChangeStr = changeArray.map(([unit, amount]) => `${unit}: $${amount.toFixed(2)}`).join(' ')

But I have all of that logic in the else statement that checks (cidTotal > change)

if (cashInputVal > price) {
    if(cidTotal < change){
      status = "INSUFFICIENT_FUNDS";
      changeDue.innerText =`Status: ${status}`;
    }
    else if(cidTotal === change){
      status = "CLOSED";
      changeDue.innerText =`Status: ${status}`;
    }
    //if(cidTotal > change)
     else{
      status = "OPEN";
      // IRL I would start with the largest bills and remove them from the register by subtracting, 
      // like if I had $17.34 I would see how many tens I need, then how many fives, then ones, then quarters and dimes etc.
      // and subtracting my change from each unit/denomination and updating the array
      

      const unitValues = {
        "PENNY": 0.01,
        "NICKEL": 0.05,
        "DIME": 0.10,
        "QUARTER": 0.25,
        "ONE": 1.00,
        "FIVE": 5.00,
        "TEN": 10.00,
        "TWENTY": 20.00,
        "ONE HUNDRED": 100.00
      };

      
      // loop backwards thru the 2d array cid array big numbers/bills are first
      for (let i = cid.length - 1; i >= 0; i--){
        // destructure inner array to break it up into units/denominations and cash
        let [unit, amount] = cid[i];
        let unitValue = unitValues[unit];
        let amountToGive = 0;

        // while money of that denomination is available in draw
        // and still change to be givrn back
        while (amount >= unitValue && unitValue <= change) {
          //update change
          change = parseFloat((change - unitValue).toFixed(2));
          //update emount of cash in drawer
          amount = parseFloat((amount - unitValue).toFixed(2));
          //update amount to give
          amountToGive = parseFloat((amountToGive + unitValue).toFixed(2));
          console.log('end of while loop?');
        }
        //populate the change array
        if (amountToGive > 0) {
          changeArray.push([unit, amountToGive]);
        }

      }
      if (change > 0) {
        console.log(`change is: ${change}`)
        // couldn't give back full change
        status = "INSUFFICIENT_FUNDS";
        changeDue.innerText = `Status: ${status}`;
        return;
      }

      if (cidTotal === calculateChange(cashInputVal, price)) {
        status = "CLOSED";
        changeArray = [...cid];
      }
      else {
        status = "OPEN";
      }
      const formattedChangeStr = changeArray.map(([unit, amount]) => `${unit}: $${amount.toFixed(2)}`).join(' ')
      changeDue.innerText = `Status: ${status} ${formattedChangeStr}`;
    }
  }
})
24

So are the contents of changeArray correct?

25

I believe so since the first 17 tests are passing.

26

You don’t need to believe. You should check for this specific test case.

27

OK. Not sure why but I am trying to log the str to console but it is not showing up:

Screenshot 2025-06-25 at 6.16.43 PM
Screenshot 2025-06-25 at 6.16.43 PM1920×1126 152 KB

28

So a return is being triggered before that point probably?

29

I thinks o but the only return I have is here:


      if (change > 0) {
        console.log(`change is: ${change}`)
        // couldn't give back full change
        status = "INSUFFICIENT_FUNDS";
        changeDue.innerText = `Status: ${status}`;
        return;
      }

And if I remove that return test cases 16 and 17 fail.

    1. When price is 19.5, the value in the #cash element is 20, cid is [["PENNY", 0.01], ["NICKEL", 0], ["DIME", 0], ["QUARTER", 0], ["ONE", 1], ["FIVE", 0], ["TEN", 0], ["TWENTY", 0], ["ONE HUNDRED", 0]], and the #purchase-btn element is clicked, the value in the #change-due element should be "Status: INSUFFICIENT_FUNDS".

  • Failed:17. When price is less than the value in the #cash element, total cash in drawer cid is greater than change due, but the individual denomination amounts make it impossible to return needed change, when the #purchase-btn element is clicked, the value in the #change-due element should be "Status: INSUFFICIENT_FUNDS"

30

So why is that check falsely triggering?

31

I’m not really sure why.

32

You should investigate that. Understanding that is likely key. I would guess it might be a floating point issue.

33

Ah I see I’ll take a closer look at that later. Thank you.

34

Ok so the issue was I was completely ignored the creation of a new array/results string with the expected change in the case where the money in the draw was equal to the change due

else if(cidTotal === change){
 status = "CLOSED";
      // make changeArray new array that includes only the denominations from cid that have amount of money > 0
      // _ makes it so you ignore the unit name, looking only at the amount
      changeArray = cid.filter(([_, amount]) => amount > 0);
      //fix format
      const formattedChangeStr = changeArray.map(([unit, amount]) => `${unit}: $${amount.toFixed(2)}`).join(' ');
      changeDue.innerText = `Status: ${status} ${formattedChangeStr}`;
      return;}

After adding this logic my code passes all the tests and I have completed this project!!