javascript - js中的数学运算？

Question

我正在尝试用 JS 创建一个简单的零钱计算器应用程序。我可以用我的美元和 25 美分找零，但在使用 dimes 时遇到了麻烦。到目前为止，这是我的代码。每次我尝试让硬币发挥作用时，我都无法打印出正确的数量。

var dollars, quarters, dimes, nickels;

function calculateChange() {
  var amountDue = document.getElementById('amount-due').value;
  var amountReceived = document.getElementById('amount-received').value;
  var change = amountReceived - amountDue;
  //document.getElementById('change-output').innerHTML = change.toFixed(2);

  dollars = Math.floor((change / 100) * 100);
  document.getElementById("dollars-output").innerHTML = dollars;
  var remainder = change - dollars;
  console.log(dollars)

  quarters = Math.floor((change % 1) * 4);
  document.getElementById('quarters-output').innerHTML = quarters;
  console.log(quarters)

  dimes = Math.floor((change % 15) * 0.10);
  document.getElementById('dimes-output').innerHTML = dimes;
  console.log(dimes)
  return;

  // = Math.floor((change % 0.1) * 20);
  //document.getElementById('nickels-output').innerHTML = nickels;

  // pennies =  Math.floor(Math.round(change % 0.05 * 100));
  //document.getElementById('pennies-output').innerHTML = pennies;

};

document.getElementById("calculate-change").addEventListener("click", calculateChange);

Amount due: <input id="amount-due"><br>
Amount-received: <input id="amount-received"><br>
<input type="button" value="Calculate change" id="calculate-change"><br>
Dollars: <span id="dollars-output"></span><br>
Quarters: <span id="quarters-output"></span><br>
Dimes: <span id="dimes-output"></span>

有人可以帮我看看有什么不同吗？

Answer 1

(change/100) * 100 与 change 相同(除非存在浮点舍入误差)，所以 Math.floor((change/100 ) * 100) 与 Math.floor(change) 相同。你应该只计算部门的下限，例如

dollars = Math.floor(change/100);

然后将其乘以 100 并从 change 中减去它以获得您需要用较小面额处理的余数。对于每种面额，您除以该硬币的值(value)，得到它的底部，然后减去得到下一个余数。

var dollars, quarters, dimes, nickels;

function calculateChange() {
  var amountDue = document.getElementById('amount-due').value;
  var amountReceived = document.getElementById('amount-received').value;
  var change = amountReceived - amountDue;
  //document.getElementById('change-output').innerHTML = change.toFixed(2);

  var dollars = Math.floor(change / 100);
  document.getElementById("dollars-output").innerHTML = dollars;
  var remainder = change - dollars * 100;

  var quarters = Math.floor(remainder / 25);
  document.getElementById('quarters-output').innerHTML = quarters;
  remainder = remainder - quarters * 25;

  var dimes = Math.floor(remainder / 10);
  document.getElementById('dimes-output').innerHTML = dimes;
  remainder = remainder - dimes * 10;

  var nickels = Math.floor(remainder/5);
  document.getElementById('nickels-output').innerHTML = nickels;
  remainder = remainder - nickels * 5;

  var pennies = remainder;
  document.getElementById('pennies-output').innerHTML = pennies;

};

document.getElementById("calculate-change").addEventListener("click", calculateChange);

Amount due: <input id="amount-due"><br>
Amount-received: <input id="amount-received"><br>
<input type="button" value="Calculate change" id="calculate-change"><br>
Dollars: <span id="dollars-output"></span><br>
Quarters: <span id="quarters-output"></span><br>
Dimes: <span id="dimes-output"></span><br>
Nickels: <span id="nickels-output"></span><br>
Pennies: <span id="pennies-output"></span><br>