Javascript 公式语法无效

Question

我有以下公式，我正在尝试将其转换为 JavaScript：

=(x*(y/120000)*(1+(y/120000))^(z))/((1+(y/120000))^z-1)

我用过下面的，但我不认为语法是正确的，但我不知道为什么！

var price = ((parseInt(x.value)*(parseInt(y.value)/1200)*(Math.pow(1+parseInt(y.value)/12000)),parseInt(z.value))) / (Math.pow((1+(parseInt(y.value)/1200),(parseInt(z.value)-1)));

我的整个表单脚本如下：

<form name="priceCalc" action="">
  <div align="center">
    <select name="loanamount" onchange="price();">
      <option value="130000">£130,000</option>
      <option value="160000">£160,000</option>
    </select>

    <select name="interestrate" onchange="price();">
      <option value="449">4.49%</option>
      <option value="500">5%</option>
    </select>

    <select name="numberpayments" onchange="price();">
      <option value="480">40yrs</option>
      <option value="360">30yrs</option>
    </select>

    <br>
    <div id="prices">Change items to see price</div>
  </div>
</form>

<script>
  function price() {
    var x = document.priceCalc.loanamount;
    var y = document.priceCalc.interestrate;
    var z = document.priceCalc.numberpayments;

    var price = ((parseInt(x.value)*(parseInt(y.value)/1200)*(Math.pow(1+parseInt(y.value)/12000)),parseInt(z.value))) / (Math.pow((1+(parseInt(y.value)/1200),(parseInt(z.value)-1)));

    document.getElementById("prices").innerHTML = 'Price: ' + price;
  }
</script>

如有任何帮助，我们将不胜感激！

谢谢

Answer 1

var price = ((parseInt(x.value)*(parseInt(y.value)/120000)*(Math.pow(1+parseInt(y.value)/120000),parseInt(z.value))) / (Math.pow((1+(parseInt(y.value)/120000),(parseInt(z.value)-1)))));

此外，在你的第一行你有 /120000 但在你的计算中你有 /1200

同样根据 gillesc 的建议：

var x = parseInt(x.value);
var y = parseInt(y.value);
var z = parseInt(z.value);
var price = ((x*(y/120000)*(Math.pow((1+y)/120000),z)) / (Math.pow((1+(y/120000),(z-1)))));

Answer 2

=(x*(y/120000)*(1+(y/120000))^(z))/((1+(y/120000))^z-1)

翻译成

var x = parseInt(x.value,10), 
    y = parseInt(y.value,10)/120000, 
    z = parseInt(z.value,10)*12; // from your comments


var price = ( x*y*Math.pow(1+y,z) ) / (Math.pow(1+y,z)-1);
document.getElementById("prices").innerHTML ='Monthly repayment: £' + price.toFixed(2);

这是您的代码

window.onload = function() {
  document.priceCalc.loanamount.onchange = price;
  document.priceCalc.interestrate.onchange = price;
  document.priceCalc.numberpayments.onchange = price;

}

function price() {

    var x = parseInt(document.priceCalc.loanamount.value, 10);
    var y = parseInt(document.priceCalc.interestrate.value, 10) / 12000; 
    var z = parseInt(document.priceCalc.numberpayments.value,10)*12;

    var repayment = (x * y * Math.pow(1 + y, z)) / (Math.pow(1 + y, z) - 1); 
    console.log(x,y,z,x * y * Math.pow(1 + y, z),(Math.pow(1 + y, z) - 1),repayment)
  
    document.getElementById("prices").innerHTML = 'Monthly repayment: £' + isFinite(repayment) && !isNaN(repayment) && repayment != Number.POSITIVE_INFINITY?repayment.toFixed(2):"0.00";
}

<form name="priceCalc" action="">
  <div align="center">

    <select name="loanamount">
      <option value="0">Please select</option>
      <option value="130000">£130,000</option>
      <option value="160000">£160,000</option>
    </select>

    <select name="interestrate">
      <option value="0">Please select</option>
      <option value="449">4.49%</option>
      <option value="500">5%</option>
    </select>

    <select name="numberpayments">
      <option value="0">Please select</option>
      <option value="480">40yrs</option>
      <option value="360">30yrs</option>
    </select>

    <br>
    <div id="prices">Change items to see price</div>
  </div>
</form>

Answer 3

请尝试以下更新的公式：-

  var price = ((parseInt(x.value) * (parseInt(y.value) / 1200) * (Math.pow(((parseInt(1) + parseInt(y.value) / 12000)), parseInt(z.value)))) / (Math.pow((parseInt(1) + (parseInt(y.value) / 1200)), (parseInt(z.value) - 1))));

Answer 4

最后找到了方法：

window.onload = function() {
  document.repaymentcalc.loanamount.onchange = repayment;
  document.repaymentcalc.interestrate.onchange = repayment;
  document.repaymentcalc.numberpayments.onchange = repayment;

}

function repayment() {

  var x = parseInt(document.repaymentcalc.loanamount.value, 10);
  var y = parseInt(document.repaymentcalc.interestrate.value, 10) / 120000;
  var z = parseInt(document.repaymentcalc.numberpayments.value, 10) * 12;

  var repayment = y * x * Math.pow((1 + y), z) / (Math.pow((1 + y), z) - 1);

  document.getElementById("repayments").innerHTML = 'Monthly repayment: £' + repayment.toFixed(2);
}

<form name="repaymentcalc" action="">
  <div align="center">
    </br>
    Loan Amount
    <select name="loanamount">
      <option value="100000">£100,000</option>
      <option value="200000">£200,000</option>
      <option value="300000">£300,000</option>
      <option value="400000">£400,000</option>
    </select>
    </p>
    Interest Rate
    <select name="interestrate">
      <option value="100">1.00%</option>
      <option value="200">2.00%</option>
      <option value="300">3.00%</option>
    </select>
    </p>
    Term
    <select name="numberpayments">
      <option value="5">5yrs</option>
      <option value="10">10yrs</option>
    </select>
    </p>
    <br>
    <div id="repayments">Monthly repayment: £837.85</div>
  </div>
</form>

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