Javascript:更改第三个输入值时的金额计算

Question

我计算了三个字段:系数、 Material 成本和制造成本。
首先计算其coef * Material 成本，得出制造成本投入。
总金额的计算是 Material 成本*制造成本，但我需要改变制造成本金额并获得总结果的能力
这该怎么做？
我的代码:

function sum(el) {
  let coefEl = document.getElementById('coef');
  let entrPriceEl = document.getElementById('enterence_price');
  let extraEl = document.getElementById('extra');
  let priceEl = document.getElementById('price');
  let extraresultEl;
  let result;
  if (el.id === "enterence_price" || el.id === "extra" || el.id === "coef") {
    extraextraresultEl = parseFloat(coefEl.value) * parseFloat(entrPriceEl.value);
    extraEl.value = extraextraresultEl;
    result = (parseFloat(entrPriceEl.value) * parseFloat(coefEl.value) + parseFloat(extraEl.value));
    if (!isNaN(result)) {
      priceEl.value = result.toFixed(2);
    }
  } else if (el.id === "enterence_price" || el.id === "extra" || el.id === "coef") {
    result = parseFloat(entrPriceEl.value) * parseFloat(extraEl.value);
    if (!isNaN(result)) {
      priceEl.value = result;
    }
  }
}

<label>Coefficient<br></label>
<input type="text" value="2" id="coef" onkeyup="sum(this);">
<br>
<label>The cost of materials<br></label>
<input type="text" value="2000" id="enterence_price" onkeyup="sum(this);">
<br>
<label>Manufacturing cost<br></label>
<input type="text" id="extra" onkeyup="sum(this);">
<br>

<label>Sum<br></label>
<input type="text" id="price" onkeyup="sum(this);">
<br>

Answer 1

您需要对 mf 成本输入应用不同的函数，因为如果您使用相同的函数，它永远不会让您更改值，因为它的值也是从您为以上 2 个值编写的相同函数中生成的
如果您需要其他东西，请随时发表评论

let coefEl = document.getElementById('coef');
  let entrPriceEl = document.getElementById('enterence_price');
  let extraEl = document.getElementById('extra');
  let priceEl = document.getElementById('price');
function sum(el) {
  
  let extraresultEl;
  if (el.id === "enterence_price" || el.id === "extra" || el.id === "coef") {
    extraextraresultEl = parseFloat(coefEl.value) * parseFloat(entrPriceEl.value);
    extraEl.value = extraextraresultEl;
    result = (parseFloat(entrPriceEl.value) * parseFloat(coefEl.value) + parseFloat(extraEl.value));
    if (!isNaN(result)) {
      priceEl.value = result.toFixed(2);
    }
  } else if (el.id === "enterence_price" || el.id === "extra" || el.id === "coef") {
    result = parseFloat(entrPriceEl.value) * parseFloat(extraEl.value);
    if (!isNaN(result)) {
      priceEl.value = result;
    }
  }
}

function canBeChnaged(el){
  var coefVal = parseInt(coefEl.value);
  var costofMatVal = parseInt(entrPriceEl.value);
  var mfCostVal = parseInt(extraEl.value);
  var finalSum = (coefVal * costofMatVal) + mfCostVal;
  priceEl.value = finalSum.toFixed(2);
}

<label>Coefficient<br></label>
<input type="text" value="2" id="coef" onkeyup="sum(this);">
<br>
<label>The cost of materials<br></label>
<input type="text" value="2000" id="enterence_price" onkeyup="sum(this);">
<br>
<label>Manufacturing cost<br></label>
<input type="text" id="extra" onkeyup="canBeChnaged(this);">
<br>

<label>Sum<br></label>
<input type="text" id="price" onkeyup="sum(this);">
<br>