javascript if else 使用数学为字段添加值不起作用

Question

无法让它发挥作用，盯着它看瞎了。有任何想法吗？如果值 kg 高于 * 的乘积，则尝试将值 kg 放入 lbh 字段中m3总计 (l*****b*****h/100000/00035)*。它用于计算货件的运费。

它用于 if else 中的计算，我想我在这里遗漏了一些东西。

function add() {
  var m3 = parseInt(document.getElementById("m3").value);
  var kg = parseInt(document.getElementById("kg").value);
  var l = parseInt(document.getElementById("L").value);
  var b = parseInt(document.getElementById("B").value);
  var h = parseInt(document.getElementById("H").value);
  var x = 0.0035;
  var y = 3350;


  var total = 0;
  kg = +kg || 0
  m3 = +m3 || 0
  l = +l || 0
  b = +b || 0
  h = +h || 0
  total = Math.ceil((m3total / 0.0035));
  kgtotal = (kg + 0)
  m3total = (l * b * h) / 1000000;
  (document.getElementById("m3").value) = m3total;
}
if ((total > kgtotal)) {

  (document.getElementById("LBvekt").value) = total;

} else if ((total < kgtotal)) {
  (document.getElementById("LBvekt").value) = kgtotal;
}

<p>Click the button</p>

<button onclick="add()">Try it</button>

<p id="demo"></p>


<div class="form-group">
  <div class="col-sm-6 col-sm-offset-3">
    <div class="row gutter-sm">


      <div class="col-sm-3 m-b-15 m-sm-b-0">
        <input type="text" class="form-control" id="kg" name="kg" placeholder="KG" onChange="add()">
      </div>
      <div class="col-sm-3 m-b-15 m-sm-b-0">
        <input type="text" class="form-control" id="m3" name="m3" placeholder="m3" readonly>
      </div>
      <div class="col-sm-3 m-b-15 m-sm-b-0">
        <input type="text" class="form-control" name="LBvekt" id="LBvekt" placeholder="LBvekt">
      </div>

    </div>
  </div>
</div>

<div class="form-group">
  <div class="col-sm-6 col-sm-offset-3">
    <div class="row gutter-sm">


      <div class="col-sm-3 m-b-15 m-sm-b-0">
        <input type="text" class="form-control" id="L" name="L" placeholder="L (cm)">
      </div>
      <div class="col-sm-3 m-b-15 m-sm-b-0">
        <input type="text" class="form-control" id="B" name="B" placeholder="B (cm)">
      </div>
      <div class="col-sm-3 m-b-15 m-sm-b-0">
        <input type="text" class="form-control" id="H" name="H" placeholder="H (cm)" onChange="add()">
      </div>

    </div>
  </div>
</div>

Answer 1

假设代码片段中的代码是您的实际代码，您的 if 语句仅执行一次:页面加载时。它位于 add() 函数之外，因此仅在加载时执行。

您很可能希望将 if 语句放在 add() 函数中，如下所示:

function add() {
  var m3 = parseInt(document.getElementById("m3").value);
  var kg = parseInt(document.getElementById("kg").value);
  var l = parseInt(document.getElementById("L").value);
  var b = parseInt(document.getElementById("B").value);
  var h = parseInt(document.getElementById("H").value);
  var x = 0.0035;
  var y = 3350;


  var total = 0;
  kg = +kg || 0
  m3 = +m3 || 0
  l = +l || 0
  b = +b || 0
  h = +h || 0
  m3total = (l * b * h) / 1000000;
  total = Math.ceil((m3total / 0.0035));
  kgtotal = (kg + 0)
  
  (document.getElementById("m3").value) = m3total;
  if ((total > kgtotal)) {

    (document.getElementById("LBvekt").value) = total;

  } else if ((total < kgtotal)) {
    (document.getElementById("LBvekt").value) = kgtotal;
  }
}

<p>Click the button</p>

<button onclick="add()">Try it</button>

<p id="demo"></p>


<div class="form-group">
  <div class="col-sm-6 col-sm-offset-3">
    <div class="row gutter-sm">


      <div class="col-sm-3 m-b-15 m-sm-b-0">
        <input type="text" class="form-control" id="kg" name="kg" placeholder="KG" onChange="add()">
      </div>
      <div class="col-sm-3 m-b-15 m-sm-b-0">
        <input type="text" class="form-control" id="m3" name="m3" placeholder="m3" readonly>
      </div>
      <div class="col-sm-3 m-b-15 m-sm-b-0">
        <input type="text" class="form-control" name="LBvekt" id="LBvekt" placeholder="LBvekt">
      </div>

    </div>
  </div>
</div>

<div class="form-group">
  <div class="col-sm-6 col-sm-offset-3">
    <div class="row gutter-sm">


      <div class="col-sm-3 m-b-15 m-sm-b-0">
        <input type="text" class="form-control" id="L" name="L" placeholder="L (cm)">
      </div>
      <div class="col-sm-3 m-b-15 m-sm-b-0">
        <input type="text" class="form-control" id="B" name="B" placeholder="B (cm)">
      </div>
      <div class="col-sm-3 m-b-15 m-sm-b-0">
        <input type="text" class="form-control" id="H" name="H" placeholder="H (cm)" onChange="add()">
      </div>

    </div>
  </div>
</div>