Question

我想计算表单中的selectbox值。例如：item price * Quantity。

如果我在表单中只有一个计算，它可以正常工作：

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)
}

任何人都可以帮我修复它吗？我很感激。我还发布了一张关于它在网页上给我的结果的图片。

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"  width="800">
<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'],'>',$row['Motherboard_Part_Number'],'&nbsp;&nbsp;&nbsp;',$row['Motherboard_Name'],' &nbsp;&nbsp;&nbsp;$',$row['Motherboard_Price'],'&nbsp;','</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'],'>',$row['Chassis_Part_Number'],'&nbsp;&nbsp;&nbsp;',$row['Chassis_Name'],' &nbsp;&nbsp;&nbsp;$',$row['Chassis_Price'],'&nbsp;','</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>

Answer 1

你正在尝试对字符串进行数学运算。尝试：

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)
}

如果你不需要花车，请使用

或parseInt。

计算选择框值

1 个答案: