Javascript计算不像预期那样工作

Question

我有一个gridview，其中有一个行，其中我添加了整数值，比如7000。

因此，如果添加了2-3行，我希望添加所有这些行值，并在textbox中显示它。

为此，我编写了以下代码

if (document.getElementById('txtTotalExp').value == "") {
            var Expense = 0;
        } else {
            var Expense = document.getElementById('txtTotalExp').value;
        }
        for (var i = 0; i < GridExpInfo.Rows.length; i++) {
            var totAmount = GridExpInfo.Rows[i].Cells[7].Value;
            var totval = totAmount;
            Expense += parseInt(totval);
        }

document.getElementById('txtTotalLandVal').value = parseInt(TotalPayableValue) + parseInt(Expense);

但在文本框中，出现了类似于200010001512的内容。

加法操作不工作。

Answer 1

我把你的问题解释为你有一个有几行值的表，你想要和每一行，然后你想得到整个表的总和。

我想提供一个工作代码片段来演示您的问题的解决方案。但是，因为您没有提供所有必要的代码，所以我发明了一些代码。在这样做的过程中，我提供了一种替代的，也许更现代的方法来解决我认为你正在试图解决的整体问题。是的，它提供的比您所要求的要多得多(...I认为讨论parseInt的其他一些答案可能解决您最初的问题)，但希望这能给您提供一些更深入的见解。

下面的示例展示了如何使用JavaScript的许多最新特性来实现这一点。希望这些评论能够详细地解释每一步发生的事情，让你对逻辑有一种感觉。要理解每一步，您可能需要深入学习更多的JavaScript。一个很好的参考是Mozilla开发者网络(MDN)，它包含关于所有这些特性的文档。

​

// when the button is clicked, do the following...
document.querySelector('button').onclick = () => {

  // calculate the total sum across the table
  const rowSums =

    // get a nodeList of all table rows in the entire document
    // and convert that array-like nodeList to a true array
    // of table row elements
    [...document.querySelectorAll('tr')]

      // remove the first row, i.e. ignore the row of column headers
      .slice(1)

      // from the original array of table rows (minus the first row)
      // create a new array in which each element is derived
      // from the corresponding table row from the original array
      .map(row => {

        // calculate the sum of values across this row
        const rowSum =

          // get a nodeList of all table cells in this row
          // and convert that array-like nodeList to a true array
          // of table cell elements
          [...row.querySelectorAll('td')]

            // remove the last cell, i.e. ignore the cell that will eventually
            // hold the sum for this row
            .slice(0,-1)

            // from the array of table cells for this row (minus the last one)
            // derive a new single value by progressively doing something
            // for each cell
            .reduce(

              // for each table cell in this row, remember the cell itself
              // as well as the accumulating value we are gradually deriving from all
              // the cells in this row, i.e. the sum of all values across this row
              (accumulatingRowSum, cell) =>

                // for each cell in this row, add the numerical value
                // of the current cell to the sum of values we are accumulating
                // across this row
                accumulatingRowSum + parseInt(cell.innerHTML, 10),

              // start our accumulating sum of values across this row with zero
              0
            );

        // get all the cells in this row
        const rowCells = row.querySelectorAll('td');

        // put the sum of values from this row into the last cell of the row
        rowCells[rowCells.length - 1].innerHTML = rowSum;

        // place the sum of values in this row into the accumulating array
        // of all such values for all rows
        return rowSum;
  });
  
  // calculate the total sum for the whole table
  const totalExpenses =

    // start with the array of sums for each row
    rowSums

      // similar to `reduce` above, reduce the array of multiple row sums
      // into a single value of the total sum, calculated by adding together
      // all the individual row sums, starting with zero
      .reduce((accumulatingTotalSum, rowTotal) => accumulatingTotalSum + rowTotal, 0);

  // place the total sum into the appropriate span element
  document.querySelector('#txtTotalExp').innerHTML = totalExpenses;
};

table {
  border: solid black 1px;
  border-collapse: collapse;
}
th, td {
  border: solid black 1px;
  padding: 0.5em;
}

<table>
  <tr><th>col1</th><th>col2</th><th>row total</th></tr>
  <tr><td>3500</td><td>1200</td><td></td></tr>
  <tr><td>2700</td><td>4500</td><td></td></tr>
  <tr><td>3100</td><td>1300</td><td></td></tr>
</table>
<p>The total expenses are: <span id="txtTotalExp"></span></p>
<button>Calculate</button>

​

Answer 2

您可以使用以下代码：

var total=parseInt(TotalPayableValue,10) + parseInt(Expense,10);
    document.getElementById('txtTotalLandVal').value=total;

Answer 3

试试这个：

var Expense = 0;
if (document.getElementById('txtTotalExp').value != "") {
 var Expense = parseInt(document.getElementById('txtTotalExp').value);
}
for (var i = 0; i < GridExpInfo.Rows.length; i++) {
 var totAmount = GridExpInfo.Rows[i].Cells[7].Value;
 Expense += parseInt(totAmount);
}

问题是:最初的开销可以是字符串。您是否尝试过如果使用“费用= 0”，就会发生错误？