根据用户html-select输出字符串

Question

我有一个表单，用户输入一个数量从1到10，和一个只读文本字段，我需要输出一个字符串与计算的价格。也可能是另一个容器之王，但由于该位置位于格式化单元格内，所以我不愿使用div。如前所述，任何东西都是在表单中为购买过程将值(也有captcha )发布到php文件中。以下是我的代码：

​

function calculatePrice() {
  var form = document.getElementById('buy_form');
  var num_pieces = parseInt(form.elements.number_select.value);
  var price_for_1 = 9.90; //I know, hardcoded is worst, I'll take it from the DB later on
  var totalprice = price_for_1 * num_pieces;
  document.getElementById("total_price").innerHTML = "Total price: \u20AC " + totalprice;
}

<form method="post" id="buy_form" action="buy.php">

<select name="numberselect" id="number_select" onChange="calculatePrice()">
<option value="1">1</option>
<option value="2">2</option>
<option value="3">3</option>
<option value="4">4</option>
<option value="5">5</option>
<option value="6">6</option>
<option value="7">7</option>
<option value="8">8</option>
<option value="9">9</option>
<option value="10">10</option>
</select>

<input type=text class="totalprice" id="total_price" style="border: none" readonly>

//a captcha image
//a captcha input field
//a submit button

</form>

​

函数根本不输出只读文本字段中的任何内容。我遗漏了什么？

Answer 1

document.getElementById("total_price").innerHTML 

应该是，

document.getElementById("total_price").value

​

function calculatePrice() {
        var form = document.getElementById('buy_form');
        var num_pieces = parseInt(form.elements.number_select.value);
        var price_for_1 = 9.90; //I know, hardcoded is worst, I'll take it from the DB later on
        var totalprice = price_for_1 * num_pieces;
        document.getElementById("total_price").value = "Total price: \u20AC " + totalprice;
    }

<form method="post" id="buy_form" action="buy.php">

    <select name="numberselect" id="number_select" onChange="calculatePrice()">
        <option value="1">1</option>
        <option value="2">2</option>
        <option value="3">3</option>
        <option value="4">4</option>
        <option value="5">5</option>
        <option value="6">6</option>
        <option value="7">7</option>
        <option value="8">8</option>
    </select>

    <input type=text class="totalprice" id="total_price" style="border: none" readonly>
</form>

​

Answer 2

实际上问题是

 document.getElementById("total_price").innerHTML

innerHTML将永远无法工作，因为innerHTML将在javascript中获取的元素上添加HTML元素。

应该用，

document.getElementById("total_price").value

所以函数将如下所示

function calculatePrice() { 
  var form = document.getElementById('buy_form');
  var num_pieces = parseInt(form.elements.number_select.value);
  var price_for_1 = 9.90; //I know, hardcoded is worst, I'll take it from the DB later on
  var totalprice = price_for_1 * num_pieces;
  document.getElementById("total_price").value = "Total price: \u20AC " + totalprice;
}

希望这能帮上忙

Answer 3

在您的JavaScript代码中执行以下更改：

function calculatePrice() {
  var form = document.getElementById('buy_form');
  var num_pieces = parseInt(form.elements.number_select.value);
  var price_for_1 = 9.90; //I know, hardcoded is worst, I'll take it from the DB later on
  var totalprice = price_for_1 * num_pieces;
  document.getElementById("total_price").value = "Total price: \u20AC " + totalprice;
}

window.calculatePrice = calculatePrice;

1. 将innerHTML更改为值。
2. 将函数添加到窗口对象中。