Question

您好，并提前感谢您。

我有一个表格，其中一些值预填充（如111.36），但当我尝试使用数字进行数学计算，或甚至显示数字时没有任何反应。

感谢您的协助， Marc（Javascript新增）

function calculate_it() {

    window.alert("In function calculate_it");

    var x = document.getElementByID("Numb01").value;
    window.alert(x);

  } //end function

<!DOCTYPE html>
<html>

<head>
  <meta charset="utf-8">
  <TITLE>Javascript Table</TITLE>
  <link href="style.css" type="text/css" rel="stylesheet">
</head>

<body>

  <h3>A demonstration of calculators</h3>

  <table id="t01">
    <caption>Chek this out!</caption>

    <tr>
      <th>Date</th>
      <th>Number 1</th>
      <th>Number 2</th>
      <th>Number 3</th>
      <th>Number 4</th>
    </tr>

    <tr>
      <td>
        <input type="text" id="Date01" value="WED21DEC16" size="10" />
      </td>
      <td>
        <input type="number" id="Numb01" value=111.36 size="5" />
      </td>
      <td>
        <input type="number" id="Numb02" value=222.36 size="5" />
      </td>
      <td>
        <input type="number" id="Numb03" value=333.36 size="5" />
      </td>
      <td>
        <input type="number" id="Numb04" value=444.36 size="5" />
      </td>
    </tr>


    <tr>
      <td>
        <input type="text" id="Date02" value="WED22DEC16" size="10" />
      </td>
      <td>
        <input type="number" id="Numb05" value=555.36 size="5" />
      </td>
      <td>
        <input type="number" id="Numb06" value=666.36 size="5" />
      </td>
      <td>
        <input type="number" id="Numb07" value=777.36 size="5" />
      </td>
      <td>
        <input type="number" id="Numb08" value=888.36 size="5" />
      </td>
    </tr>


    <TR>
      <td height="20" ColSpan="5"></td>
    </TR>

    <TR>
      <td height="20" ColSpan="2"></td>
      <td ColSpan="2" class='alnright'>Multiply:</td>
      <td>
        <input type="text" id="ActionMulti" value="" size="5" />
      </td>
    </TR>

    <TR>
      <td height="20" ColSpan="2"></td>
      <td ColSpan="2" class='alnright'>Add:</td>
      <td>
        <input type="text" id="ActionAdd" value="" size="5" />
      </td>
    </TR>

    <TR>
      <td height="20" ColSpan="2"></td>
      <td ColSpan="2" class='alnright'>Percentage:</td>
      <td>
        <input type="text" id="ActionPercentage" value="" size="5" />
      </td>
    </TR>

    <TR>
      <td height="20" ColSpan="2"></td>
      <td ColSpan="2" class='alnright'>----------</td>
      <td>--------</td>
    </TR>

    <TR>
      <td height="20" ColSpan="2"></td>
      <td ColSpan="2" class='alnright'>Sum:</td>
      <td>
        <input type="text" id="Sum" value="" size="5" />
      </td>
    </TR>

  </table>
  <br>

  <p>Click the button to calculate the data</p>
  <button type="button" onclick="calculate_it()">calculate_it</button>

</body>

</html>

Answer 1

好吧，我猜你已经读过所有评论相同的评论：getElementById而不是getElementByID。请注意，JavaScript 区分大小写。

成功运行代码需要做的只是简单的两件事：

将所有输入（数字）值存储在数组中。
使用缩减功能可以轻松获得multiply，sum和percentage的结果。

例如：

function calculate_it() {
  var inputs = document.querySelectorAll('input[type="number"]');
  var multiply = 0;
  var add = 0;
  var percentage = 0;

  // get the values of each input, map then and return
  // a new array with the parsed numbers
  var numbers = [].map.call(inputs, function (i) {
    return parseFloat(i.value);
  });

  multiply = numbers.reduce(function (n1, n2) {
    return n1 * n2;
  });
  add = numbers.reduce(function (n1, n2) {
    return n1 + n2;
  });
  percentage = numbers.reduce(function (n1, n2) {
    return (n1 / n2) * 100;
  });

  document.getElementById('ActionMulti').value = multiply.toFixed(2);
  document.getElementById('ActionAdd').value = add.toFixed(2);
  document.getElementById('ActionPercentage').value = percentage.toFixed(2);
  document.getElementById('Sum').value = (multiply + add + percentage).toFixed(2);
}

toFixed类的Number返回数字的字符串表示形式，其中最大小数位数作为参数传递。如果必要的话，它会对数字进行舍入（经典回合）。

完整示例

＆＃13;

function calculate_it() {
  var inputs = document.querySelectorAll('input[type="number"]');
  var multiply = 0;
  var add = 0;
  var percentage = 0;
  
  // get the values of each input, map then and return
  // a new array with the parsed numbers
  var numbers = [].map.call(inputs, function (i) {
  	return parseFloat(i.value);
  });
 
  multiply = numbers.reduce(function (n1, n2) {
    return n1 * n2;
  });
  add = numbers.reduce(function (n1, n2) {
    return n1 + n2;
  });
  percentage = numbers.reduce(function (n1, n2) {
  	return (n1 * n2) / 100;
  });
  
   document.getElementById('ActionMulti').value = multiply.toFixed(2);
  document.getElementById('ActionAdd').value = add.toFixed(2);
  document.getElementById('ActionPercentage').value = percentage.toFixed(8);
  document.getElementById('Sum').value = (multiply + add + percentage).toFixed(2);
}

＆＃13;

input {
  width: 100%;
}

＆＃13;

<h3>A demonstration of calculators</h3>

<table id="t01">
  <caption>Chek this out!</caption>

  <tr>
    <th>Date</th>
    <th>Number 1</th>
    <th>Number 2</th>
    <th>Number 3</th>
    <th>Number 4</th>
  </tr>

  <tr>
    <td>
      <input type="text" id="Date01" value="WED21DEC16" size="10" />
    </td>
    <td>
      <input type="number" id="Numb01" value=11.36 size="5" />
    </td>
    <td>
      <input type="number" id="Numb02" value=12.36 size="5" />
    </td>
    <td>
      <input type="number" id="Numb03" value=7.36 size="5" />
    </td>
    <td>
      <input type="number" id="Numb04" value=4.36 size="5" />
    </td>
  </tr>


  <tr>
    <td>
      <input type="text" id="Date02" value="WED22DEC16" size="10" />
    </td>
    <td>
      <input type="number" id="Numb05" value=8.36 size="5" />
    </td>
    <td>
      <input type="number" id="Numb06" value=6.36 size="5" />
    </td>
    <td>
      <input type="number" id="Numb07" value=10.36 size="5" />
    </td>
    <td>
      <input type="number" id="Numb08" value=8.36 size="5" />
    </td>
  </tr>


  <TR>
    <td height="20" ColSpan="5"></td>
  </TR>

  <TR>
    <td height="20" ColSpan="2"></td>
    <td ColSpan="2" class='alnright'>Multiply:</td>
    <td>
      <input type="text" id="ActionMulti" value="" size="5" />
    </td>
  </TR>

  <TR>
    <td height="20" ColSpan="2"></td>
    <td ColSpan="2" class='alnright'>Add:</td>
    <td>
      <input type="text" id="ActionAdd" value="" size="5" />
    </td>
  </TR>

  <TR>
    <td height="20" ColSpan="2"></td>
    <td ColSpan="2" class='alnright'>Percentage:</td>
    <td>
      <input type="text" id="ActionPercentage" value="" size="5" />
    </td>
  </TR>

  <TR>
    <td height="20" ColSpan="2"></td>
    <td ColSpan="2" class='alnright'>----------</td>
    <td>--------</td>
  </TR>

  <TR>
    <td height="20" ColSpan="2"></td>
    <td ColSpan="2" class='alnright'>Sum:</td>
    <td>
      <input type="text" id="Sum" value="" size="5" />
    </td>
  </TR>

</table>
<br>

<p>Click the button to calculate the data</p>
<button type="button" onclick="calculate_it()">calculate_it</button>

＆＃13;

对表元素进行算术运算

1 个答案: