freeCodeCamp/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/javascript-algorithms-and-data-structures-projects/cash-register.md

---
id: aa2e6f85cab2ab736c9a9b24
challengeType: 5
forumTopicId: 16012
title: 收银机
---

## Description
<section id='description'>
编写一个用于收银机的函数<code>checkCashRegister()</code>，传入售价为第一个参数（<code>price</code>）、支付金额为第二个参数（<code>cash</code>）、收银机內的金额为第三个参数（<code>cid</code>）。
<code>cid</code>是包含货币面值的二维数组。
函数<code>checkCashRegister()</code>必须返回含有<code>status</code>键值和<code>change</code>键值的对象。
如果收银机內的金额少于应找回的零钱数，或者你无法返回确切的数目时，返回<code>{status: "INSUFFICIENT_FUNDS", change: []}</code>。
如果收银机內的金额等于应找回的零钱数，返回<code>{status: "CLOSED", change: [...]}</code>，其中<code>change</code>键值是收银机內的金额。
否则，返回<code>{status: "OPEN", change: [...]}</code>，其中<code>change</code>键值是应找回的零钱数，并且它的面值由高到低排序。
<table class='table table-striped'><tr><th>货币单位</th><th>面值</th></tr><tr><td>Penny</td><td>$0.01 (PENNY)</td></tr><tr><td>Nickel</td><td>$0.05 (NICKEL)</td></tr><tr><td>Dime</td><td>$0.1 (DIME)</td></tr><tr><td>Quarter</td><td>$0.25 (QUARTER)</td></tr><tr><td>Dollar</td><td>$1 (DOLLAR)</td></tr><tr><td>Five Dollars</td><td>$5 (FIVE)</td></tr><tr><td>Ten Dollars</td><td>$10 (TEN)</td></tr><tr><td>Twenty Dollars</td><td>$20 (TWENTY)</td></tr><tr><td>One-hundred Dollars</td><td>$100 (ONE HUNDRED)</td></tr></table>
</section>

## Instructions
<section id='instructions'>

</section>

## Tests
<section id='tests'>

```yml
tests:
  - text: "<code>checkCashRegister(19.5, 20, [['PENNY', 1.01], ['NICKEL', 2.05], ['DIME', 3.1], ['QUARTER', 4.25], ['ONE', 90], ['FIVE', 55], ['TEN', 20], ['TWENTY', 60], ['ONE HUNDRED', 100]])</code>应该返回一个对象。"
    testString: assert.deepEqual(Object.prototype.toString.call(checkCashRegister(19.5, 20, [["PENNY", 1.01], ["NICKEL", 2.05], ["DIME", 3.1], ["QUARTER", 4.25], ["ONE", 90], ["FIVE", 55], ["TEN", 20], ["TWENTY", 60], ["ONE HUNDRED", 100]])), '[object Object]');
  - text: '<code>checkCashRegister(19.5, 20, [["PENNY", 1.01], ["NICKEL", 2.05], ["DIME", 3.1], ["QUARTER", 4.25], ["ONE", 90], ["FIVE", 55], ["TEN", 20], ["TWENTY", 60], ["ONE HUNDRED", 100]])</code>应该返回<code>{status: "OPEN", change: [["QUARTER", 0.5]]}</code>。'
    testString: 'assert.deepEqual(checkCashRegister(19.5, 20, [["PENNY", 1.01], ["NICKEL", 2.05], ["DIME", 3.1], ["QUARTER", 4.25], ["ONE", 90], ["FIVE", 55], ["TEN", 20], ["TWENTY", 60], ["ONE HUNDRED", 100]]), {status: "OPEN", change: [["QUARTER", 0.5]]});'
  - text: '<code>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]])</code>应该返回<code>{status: "OPEN", change: [["TWENTY", 60], ["TEN", 20], ["FIVE", 15], ["ONE", 1], ["QUARTER", 0.5], ["DIME", 0.2], ["PENNY", 0.04]]}</code>。'
    testString: 'assert.deepEqual(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]]), {status: "OPEN", change: [["TWENTY", 60], ["TEN", 20], ["FIVE", 15], ["ONE", 1], ["QUARTER", 0.5], ["DIME", 0.2], ["PENNY", 0.04]]});'
  - text: '<code>checkCashRegister(19.5, 20, [["PENNY", 0.01], ["NICKEL", 0], ["DIME", 0], ["QUARTER", 0], ["ONE", 0], ["FIVE", 0], ["TEN", 0], ["TWENTY", 0], ["ONE HUNDRED", 0]])</code>应该返回<code>{status: "INSUFFICIENT_FUNDS", change: []}</code>。'
    testString: 'assert.deepEqual(checkCashRegister(19.5, 20, [["PENNY", 0.01], ["NICKEL", 0], ["DIME", 0], ["QUARTER", 0], ["ONE", 0], ["FIVE", 0], ["TEN", 0], ["TWENTY", 0], ["ONE HUNDRED", 0]]), {status: "INSUFFICIENT_FUNDS", change: []});'
  - text: '<code>checkCashRegister(19.5, 20, [["PENNY", 0.01], ["NICKEL", 0], ["DIME", 0], ["QUARTER", 0], ["ONE", 1], ["FIVE", 0], ["TEN", 0], ["TWENTY", 0], ["ONE HUNDRED", 0]])</code>应该返回<code>{status: "INSUFFICIENT_FUNDS", change: []}</code>。'
    testString: 'assert.deepEqual(checkCashRegister(19.5, 20, [["PENNY", 0.01], ["NICKEL", 0], ["DIME", 0], ["QUARTER", 0], ["ONE", 1], ["FIVE", 0], ["TEN", 0], ["TWENTY", 0], ["ONE HUNDRED", 0]]), {status: "INSUFFICIENT_FUNDS", change: []});'
  - text: '<code>checkCashRegister(19.5, 20, [["PENNY", 0.5], ["NICKEL", 0], ["DIME", 0], ["QUARTER", 0], ["ONE", 0], ["FIVE", 0], ["TEN", 0], ["TWENTY", 0], ["ONE HUNDRED", 0]])</code>应该返回<code>{status: "CLOSED", change: [["PENNY", 0.5], ["NICKEL", 0], ["DIME", 0], ["QUARTER", 0], ["ONE", 0], ["FIVE", 0], ["TEN", 0], ["TWENTY", 0], ["ONE HUNDRED", 0]]}</code>。'
    testString: 'assert.deepEqual(checkCashRegister(19.5, 20, [["PENNY", 0.5], ["NICKEL", 0], ["DIME", 0], ["QUARTER", 0], ["ONE", 0], ["FIVE", 0], ["TEN", 0], ["TWENTY", 0], ["ONE HUNDRED", 0]]), {status: "CLOSED", change: [["PENNY", 0.5], ["NICKEL", 0], ["DIME", 0], ["QUARTER", 0], ["ONE", 0], ["FIVE", 0], ["TEN", 0], ["TWENTY", 0], ["ONE HUNDRED", 0]]});'

```

</section>

## Challenge Seed
<section id='challengeSeed'>

<div id='js-seed'>

```js
function checkCashRegister(price, cash, cid) {
  var change;
  // Here is your change, ma'am.
  return change;
}

// 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(19.5, 20, [["PENNY", 1.01], ["NICKEL", 2.05], ["DIME", 3.1], ["QUARTER", 4.25], ["ONE", 90], ["FIVE", 55], ["TEN", 20], ["TWENTY", 60], ["ONE HUNDRED", 100]]);
```

</div>



</section>

## Solution
<section id='solution'>


```js
var denom = [
	{ name: 'ONE HUNDRED', val: 100},
	{ name: 'TWENTY', val: 20},
	{ name: 'TEN', val: 10},
	{ name: 'FIVE', val: 5},
	{ name: 'ONE', val: 1},
	{ name: 'QUARTER', val: 0.25},
	{ name: 'DIME', val: 0.1},
	{ name: 'NICKEL', val: 0.05},
	{ name: 'PENNY', val: 0.01}
];

function checkCashRegister(price, cash, cid) {
 var output = {status: null, change: []};
 var change = cash - price;
 var register = cid.reduce(function(acc, curr) {
 acc.total += curr[1];
 acc[curr[0]] = curr[1];
 return acc;
 }, {total: 0});
 if(register.total === change) {
 output.status = 'CLOSED';
 output.change = cid;
 return output;
 }
 if(register.total < change) {
 output.status = 'INSUFFICIENT_FUNDS';
 return output;
 }
 var change_arr = denom.reduce(function(acc, curr) {
 var value = 0;
 while(register[curr.name] > 0 && change >= curr.val) {
 change -= curr.val;
 register[curr.name] -= curr.val;
 value += curr.val;
 change = Math.round(change * 100) / 100;
 }
 if(value > 0) {
 acc.push([ curr.name, value ]);
 }
 return acc;
 }, []);
 if(change_arr.length < 1 || change > 0) {
 output.status = 'INSUFFICIENT_FUNDS';
 return output;
 }
 output.status = 'OPEN';
 output.change = change_arr;
 return output;
}
```

</section>