计算选择框值
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【中文标题】计算选择框值【英文标题】：Calulate selectbox value 【发布时间】：2011-07-30 10:37:29 【问题描述】：我想计算表单中的选择框值。例如：item price * Quantity。
如果我在表单中只有一个计算，它就可以正常工作：
function calculate()
document.calcform.total.value =
(document.calcform.Chassis.value)*(document.calcform.Quantity.value)
但是，当我有多个计算时，它会给我NaN.00：
function calculate()
document.calcform.total.value =
(document.calcform.Motherboard.value)
*(document.calcform.Quantity.value)
+(document.calcform.Chassis.value)
*(document.calcform.Quantity1.value)
谁能帮我解决？我很感激。 我还在网页上发布了一张关于它给我的结果的图片。
这是我的代码：
<html>
<head>
<title></title>
<style type = "text/css">
.SelectClass
font-size: 15px;
table
font-size: .9em;
border: 3px groove;
padding: 0px;
background-color: #dddddd;
.mycss
font-weight:normal;font-style:italic;color:#000000;letter-spacing:1pt;word-spacing:2pt;font-size:36px;text-align:left;font-family:courier new, courier, monospace;line-height:1;
</style>
<script LANGUAGE="javascript">
function dp(price)
string = "" + price;
number = string.length - string.indexOf('.');
if (string.indexOf('.') == -1)
return string + '.00';
if (number == 1)
return string + '00';
if (number == 2)
return string + '0';
if (number > 3)
return string.substring(0,string.length-number+3);
return string;
function calculate()
document.calcform.total.value = dp((document.calcform.Motherboard.value)*(document.calcform.Quantity.value)+(document.calcform.Chassis.value)*(document.calcform.Quantity1.value))
</script>
</head>
<body onload="calculate">
<div class="mycss"><center>Order List</center></div><br />
<center>
<form name="calcform" method="post" action="test2.php">
<table border="0" >
<tr>
<td align="right" colspan="2">
<font size="6">$</font><input name="total" style="border:0px solid #000000; background-color:#E6FBF4; font-size: 25.5px;" type="text" value="0.00" ONCHANGE="calculate()"/>
</td></tr>
<tr>
<td><font size="+1">
Product Name</font>
</td>
<td><font size="+1">Quantity</font></td></tr>
<td colspan="2">
<?php
mysql_connect("host", "user", "pass") or die(mysql_error());
mysql_select_db("a4202648_wang") or die(mysql_error());
echo "<table width='100%'>";
echo "<tr><td align='left' width='90%'>";
$result = mysql_query("SELECT Motherboard_Part_Number, Motherboard_Name, Motherboard_Price FROM Motherboard where Motherboard_Part_Number='MB-435ED-3'")
or die(mysql_error());
echo '<select id="Motherboard" class="SelectClass" name="Motherboard" ONCHANGE="calculate()">';
// keeps getting the next row until there are no more to get
while($row = mysql_fetch_array( $result ))
// Print out the contents of each row into a table
echo '<option Name="Motherboard" value= ',$row['Motherboard_Price'],'>',$row['Motherboard_Part_Number'],' ',$row['Motherboard_Name'],' $',$row['Motherboard_Price'],' ','</option>';
echo '</select>';
echo "</td>";
echo "<td align='right' width='10%'>";
$result= mysql_query("SELECT Number FROM Quantity")
or die(mysql_error());
echo '<select id="Quantity" class="SelectClass" name="Quantity" Value="Quantity" ONCHANGE="calculate()" >';
// keeps getting the next row until there are no more to get
while($row = mysql_fetch_array( $result))
// Print out the contents of each row into a table
echo '<option value=',$row['Number'],'>',$row['Number'],'</option>';
echo '</select>';
echo "</td></tr>";
echo "<tr><td align='left' width='90%'>";
$result = mysql_query("SELECT Chassis_Part_Number, Chassis_Name, Chassis_Price FROM Chassis where Chassis_Form_Factor='ATX'")
or die(mysql_error());
echo '<select id="Chassis" class="SelectClass" name="Chassis" ONCHANGE="calculate()">';
// keeps getting the next row until there are no more to get
while($row = mysql_fetch_array( $result ))
// Print out the contents of each row into a table
echo '<option Name="Chassis" value= ',$row['Chassis_Price'],'>',$row['Chassis_Part_Number'],' ',$row['Chassis_Name'],' $',$row['Chassis_Price'],' ','</option>';
echo '</select>';
echo "</td>";
echo "<td align='right' width='10%'>";
$result= mysql_query("SELECT Number FROM Quantity")
or die(mysql_error());
echo '<select id="Quantity" class="SelectClass" name="Quantity1" Value="Quantity" ONCHANGE="calculate()" >';
// keeps getting the next row until there are no more to get
while($row = mysql_fetch_array( $result))
// Print out the contents of each row into a table
echo '<option value=',$row['Number'],'>',$row['Number'],'</option>';
echo '</select>';
echo "</td></tr>";
echo "</table>";
?>
</td>
</tr>
<tr><td colspan="2"><input type="submit" /></td></tr>
</table>
</form>
</center>
</body>
</html>
【问题讨论】：
【参考方案1】：您正在尝试对字符串进行数学运算。试试：
function calculate()
document.calcform.total.value =
parseFloat(document.calcform.Motherboard.value || 0)
* parseFloat(document.calcform.Quantity.value || 0)
+ parseFloat(document.calcform.Chassis.value || 0)
* parseFloat(document.calcform.Quantity1.value || 0)
如果不需要浮点数，也可以使用 parseInt。
【讨论】：
它仍然给我 NaN.00 的结果，即使我更改为 parselInt 哦。狼队。它现在显示数字，但它只给出底盘*数量的结果。看来拳头计算效果不好。 嗯，那不是数字。你有 $'s 什么的吗？ 好的，document.calcform.Motherboard.value 和 document.calcform.Quantity.value 是什么？以上是关于计算选择框值的主要内容，如果未能解决你的问题，请参考以下文章