尝试使用javascript计算订单的总成本，使用通过html中的表单输入的数量，但总数未显示在输入框中。一直在乱搞它几天，昨天显示NaN，但现在盒子保持完全空白。这些都在单个网页中作为学校的实际评估，我只是使用脚本标记。
见下面的js
function calculatePrice()
{
//select data
var cappuccino = 3.00;
var espresso = 2.25;
var latte = 2.50;
var iced = 2.50;
var quantityCappuccino = document.getElementByID("quantityCappuccino").value;
var quantityEspresso = document.getElementByID("quantityEspresso").value;
var quantityLatte = document.getElementByID("quantityLatte").value;
var quantityIced = document.getElementByID("quantityIced").value;
//calculate final cost
var total = (quantityCappuccino * cappuccino) + (quantityEspresso * espresso) + (quantityLatte * latte) + (quantityIced * iced);
//print value to orderTotal
document.getElementById("orderTotal").value=total;
}
这是表单的html
<table>
<tr align="center">
<td><hr>
Hot Drinks<hr>
</td>
<td><hr>
Price<hr>
</td>
<td><hr>
Quantity<hr>
</td>
</tr>
<form name="calcuccino">
<tr>
<td>
Cappuccino
</td>
<td align="center">
$3.00
</td>
<td align="center">
<input type="number" id="quantityCappucino" name="quantityCappuccino" value="0">
</td>
</tr>
<tr>
<td>
Espresso
</td>
<td align="center">
$2.25
</td>
<td align="center">
<input type="number" id="quantityEspresso" name="quantityEspresso" value="0">
</td>
</tr>
<tr>
<td>
Latte
</td>
<td align="center">
$2.50
</td>
<td align="center">
<input type="number" id="quantityLatte" name="quantityLatte" value="0">
</td>
</tr>
<tr>
<td>
Iced
</td>
<td align="center">
$2.50
</td>
<td align="center">
<input type="number" id="quantityIced" name="quantityIced" value="0">
</td>
</tr>
<tr>
<td>
<hr>
<input type="checkbox" id="takeaway" name="takeaway">Takeaway?</option>
</td>
</tr>
<tr>
<td>
<br>
<button type="button" onclick="calculatePrice()">Submit Order</button>
</td>
<td>
</td>
<td>
<br>
<hr>
Order total: <b>$</b>
<input type="text" name="orderTotal" id="orderTotal" Size=6 readonly>
答案 0 :(得分：0)
我发现了两个错误：
（1）在接下来的四个var语句中，getElementById而不是getElementByID（不要全押“Id”）。
（2）您的第一个<input>标记的ID名称拼写错误。它应该是quantityCappuccino（与name属性相同）。
修好后，代码就像魅力一样。
注意：我花了几秒钟才弄明白，因为错误控制台（在FireFox中，按F12键打开它）报告了问题。那个控制台是你的朋友。
答案 1 :(得分：0)
试试这个！
$("#orderTotal").click(function () {
calculatePrice();
});
function calculatePrice()
{
//select data
var cappuccino = 3.00;
var espresso = 2.25;
var latte = 2.50;
var iced = 2.50;
var quantityCappuccino = $("#quantityCappucino").val();
var quantityEspresso = $("#quantityEspresso").val();
var quantityLatte = $("#quantityLatte").val();
var quantityIced = $("#quantityIced").val();
//calculate final cost
var total = (quantityCappuccino * cappuccino) + (quantityEspresso * espresso) + (quantityLatte * latte) + (quantityIced * iced);
console.log(total);
//print value to orderTotal
$("#orderTotal").val(total);
}<!DOCTYPE html>
<html>
<head>
<title>Title of the document</title>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
</head>
<body>
<table>
<tr align="center">
<td><hr>
Hot Drinks<hr>
</td>
<td><hr>
Price<hr>
</td>
<td><hr>
Quantity<hr>
</td>
</tr>
<form name="calcuccino">
<tr>
<td>
Cappuccino
</td>
<td align="center">
$3.00
</td>
<td align="center">
<input type="number" id="quantityCappucino" name="quantityCappuccino" value="0">
</td>
</tr>
<tr>
<td>
Espresso
</td>
<td align="center">
$2.25
</td>
<td align="center">
<input type="number" id="quantityEspresso" name="quantityEspresso" value="0">
</td>
</tr>
<tr>
<td>
Latte
</td>
<td align="center">
$2.50
</td>
<td align="center">
<input type="number" id="quantityLatte" name="quantityLatte" value="0">
</td>
</tr>
<tr>
<td>
Iced
</td>
<td align="center">
$2.50
</td>
<td align="center">
<input type="number" id="quantityIced" name="quantityIced" value="0">
</td>
</tr>
<tr>
<td>
<hr>
<input type="checkbox" id="takeaway" name="takeaway">Takeaway?</option>
</td>
</tr>
<tr>
<td>
<br>
<button type="button" onclick="calculatePrice()">Submit Order</button>
</td>
<td>
</td>
<td>
<br>
<hr>
Order total: <b>$</b>
<input type="text" name="orderTotal" id="orderTotal" Size=6 readonly>
</td>
</tr>
</form>
</table>
</body>
</html>