在Javascript中将下拉字段乘以文本字段

Trying to create a calculator of sorts by using drop-down menus and quantities. How can I multiply the value from a drop-down to a text field, and have the result show up in another text field, using Javascript? This would apply to each line in the table.

尝试使用下拉菜单和数量创建各种计算器。如何将下拉值与文本字段相乘,并使用Javascript将结果显示在另一个文本字段中?这将适用于表中的每一行。

HTML:

<table width="594" border="1">
  <tr>
    <th colspan="2" scope="col"><strong>Line Breakdown</strong></th>
    <th colspan="2" scope="col"><strong>Qty</strong></th>
    <th width="90" scope="col">Unit Line Cost</th>
    <th width="90" scope="col">Total Line Cost</th>
  </tr>
  <tr>
    <td width="122"><strong>Cabinets</strong></td>
    <td width="150"><select name="DDcabinets" id="DDcabinets">
      <option value="">Select an option …</option>
      <option value="100">Dura Supreme</option>
      <option value="110">Lenape Village</option>
      <option value="120">Wellborn Forest</option>
    </select></td>
    <td width="65"><input type="text" name="Qcabinets" id="Qcabinets" size="10" maxlength="5"/></td>
    <td width="41">ft.</td>

Javascript:

window.onload = function () {
        var select1 = document.getElementById('DDcabinets');
        var input1 = document.getElementById('Vcabinets');
        select1.onchange = function () {
            input1.value = select1.value;
        };

I added this Javascript, but it's not working - I'm guessing my Javascript math is a bit off (that and I'm just really unfamiliar with the coding.)

我添加了这个Javascript,但是它不起作用 - 我猜我的Javascript数学有点不对(我真的不熟悉编码。)

        var total1 = document.getElementById('Tcabinets');
        var qty1 = document.getElementsById('Qcabinets');
        qty1.onchange = function () {
            total1.value = select1.value * qty1.value;
        };

Also see http://jsbin.com/dodew/2/edit for the full script. [NOTE: You may have to adjust the size of the "Output" column to see the entire table of dropdowns and textfields.]

另请参阅http://jsbin.com/dodew/2/edit以获取完整脚本。 [注意:您可能需要调整“输出”列的大小以查看整个下拉列表和文本字段表。]

2 个解决方案

#1

Okay so you're SUPER close, great job! The two things that you need to take note of are this.

好的,所以你非常亲密,干得好!你需要注意的两件事是这个。

// getElement(s)ById, no such thing! Change it to getElementById
var qty1 = document.getElementsById('Qcabinets');

The next thing, is the element values are stored as string, you need to convert them to integral values, I tend to do this with parseFloat, but parseInt is just as good of a choice.

接下来,将元素值存储为字符串,您需要将它们转换为整数值,我倾向于使用parseFloat,但parseInt也是一个好选择。

Just change your multiplication to convert the strings to integrals, and you're fine!

只需更改你的乘法就可以将字符串转换为积分,你就没事了!

total1.value = parseFloat(select1.value) * parseFloat(qty1.value);

2 个解决方案

#1

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