JavaScript potential FOR loop error and algorithm works on all but one value

JavaScript
1

Tell us what’s happening:
My code works correctly for other inputs however for the test where [“PENNIES”, 0.04] is expected as the last element in the array, it returns “PENNIES”, 0.03 instead. Im not sure why since the algorithm works correctly for all other values. Also, where it says “i–” inside the for loop instead of inside the bracket to declare it, I tried to put it in the bracket the normal way but I think it causes a runtime error since the for loop won’t work at all like that.

Your code so far

function checkCashRegister(price, cash, cid) {
  let output = { status: "", change: [] };
  let change = cash - price;
  
let cashVals = [
  { name: 'PENNY', val: 0.01, quant: 0},
  { name: 'NICKEL', val: 0.05, quant: 0},
  { name: 'DIME', val: 0.10, quant: 0},
  { name: 'QUARTER', val: 0.25, quant: 0},
  { name: 'ONE', val: 1.00, quant: 0},
  { name: 'FIVE', val: 5.00, quant: 0},
  { name: 'TEN', val: 10.00, quant: 0},
  { name: 'TWENTY', val: 20.00, quant: 0},
  { name: 'ONE HUNDRED', val: 100.00, quant: 0}
];

let changeGiven = [];


  // Get total
  let totalCid = 0;
for(let i = 0; i < cid.length; i++)
{
  totalCid += cid[i][1];
}
totalCid = Math.round(totalCid * 100) / 100;
  // Handle obvious insufficient funds
  if (totalCid < change) {
    output.status = 'INSUFFICIENT_FUNDS';
    return output;
  }

  // Handle exact change
  if (totalCid == change) {
    output.status = 'CLOSED';
    output.change = cid;
    return output;
  }


 for(let i = 0; i < cashVals.length;i++)
 { 
   cashVals[i].quant = cid[i][1] / cashVals[i].val;
   cashVals[i].quant = Math.round(cashVals[i].quant * 100) / 100;
   console.log(cashVals[i].quant);

 }
let val = 0;
for(let i = cashVals.length; i > 0;)
{
  i--


  while(cashVals[i].quant > 0 && change >= cashVals[i].val)
{
  change -= cashVals[i].val;
  
  cashVals[i].quant--;
  val += cashVals[i].val;

}
if(val > 0){

changeGiven.push([cashVals[i].name , val])
val = 0;
output.status = 'CLOSED';
}


}
console.log(changeGiven);
if (changeGiven.length < 1 || change > 0) 
{
    output.status = 'INSUFFICIENT_FUNDS';
    return output;
}

console.log(output.status);
console.log(output.change);

  // Here is your change, ma'am.
  output.status = 'OPEN';
  output.change = changeGiven;
  return output;
}


// Example cash-in-drawer array:
// [["PENNY", 1.01],
// ["NICKEL", 2.05],
// ["DIME", 3.1],
// ["QUARTER", 4.25],
// ["ONE", 90],
// ["FIVE", 55],
// ["TEN", 20],
// ["TWENTY", 60],
// ["ONE HUNDRED", 100]]

checkCashRegister(3.26, 100, [["PENNY", 1.01], ["NICKEL", 2.05], ["DIME", 3.1], ["QUARTER", 4.25], ["ONE", 90], ["FIVE", 55], ["TEN", 20], ["TWENTY", 60], ["ONE HUNDRED", 100]]);

Your browser information:

User Agent is: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/69.0.3497.100 Safari/537.36.

Link to the challenge:
https://learn.freecodecamp.org/javascript-algorithms-and-data-structures/javascript-algorithms-and-data-structures-projects/cash-register/

3

I have not totally traced through your code but I would guess that you may have some floating point math issue that you need to check.

Some of your math is done with floats not integers so you may be getting some imprecise calculations. Your change variable would be my first suspect but it could be any variable that’s value is the result of floating point math. console.log will root those out.

Probably you still owe the customer something like 0.009999999 dollars and can’t make change.

You might do well to calculate everything in cents, not dollars to avoid math with a fractional part entirely.
One dollar = 100 , not 1.00

4

Thank you! It took a while to implement but I got there in the end. Your help is much appreciated.

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