The exercise is: JavaScript Algorithms and Data Structures Projects: Cash Register

I struggled to understand the suggested solutions on the answer sheet. So I applied what I knew from the Roman Numeral Converter. While the answer worked, I think there’s room for improvement.

Please read and criticize my code. After many hours working on this exercise, I need a fresh pair of eyes to help me improve.

Here’s my code:

```
function checkCashRegister(price, cash, cid) {
//all money values are multiplied by 100 to deal with precision errors involved with decimals
const denomination = [10000, 2000, 1000, 500, 100, 25, 10, 5, 1,];
function transaction(price, cash, cid) {
let changeNeeded = (cash - price) * 100;
//money will be pushed to the second value in each array
let moneyProvided = [
["ONE HUNDRED", 0],
["TWENTY", 0],
["TEN", 0],
["FIVE", 0],
["ONE", 0],
["QUARTER", 0],
["DIME", 0],
["NICKEL", 0],
["PENNY", 0],
];
//take the cid, reverse it (like in Roman Numerals exercise), multiply values by 100
let availCash = [...cid].reverse().map(el => [el[0], el[1] * 100]);
//get the total sum of all cash and divide by 100
let sumOfCash = availCash.reduce((a, b) => (a + b[1]),0) / 100;
//if sumOfCash is exact change needed return
if (sumOfCash === changeNeeded / 100) {
return {status: "CLOSED", change: [...cid]};
}
//else, run this function
else for (let i = 0; i < availCash.length; i++) {
//if denomination values are less than changeNeeded and availableCash values are greater than 0, run the while loop
while (denomination[i] <= changeNeeded && availCash[i][1] > 0) {
//1. moneyProvided array is increased by denomination value
moneyProvided[i][1] += denomination[i];
//2. changeNeeded is decreased by same denomination value
changeNeeded -= denomination[i];
//3. availCash is also decreased by same denomination value
availCash[i][1] -= denomination[i];
}
};
//clean up the moneyProvided array by
let change = moneyProvided
//1. resetting the money values by dividing by 100
.map(el => [el[0], el[1] / 100])
//2. filtering out all non-empty dollar and value arrays
.filter(el => el[1] !== 0);
//calculate the total of the change array
let changeTotal = change.reduce((a, b) => (a + b[1]),0);
//if the total change is less than the change needed
if (changeTotal < changeNeeded) {
return {status: "INSUFFICIENT_FUNDS", change: []};
}
return {status: "OPEN", change};
}
//this is where the transaction function is called
let answer = transaction(price, cash, cid);
//here the final answer is provided if the 2 if statements don't catch it first
return answer;
};
```