4

我试图显示一个警告框，每次用户在下拉列表中选择不同的选项时，该框的内容都会发生变化。

这里有两个下拉列表，但是“产品”下拉列表指向同一个数组

如您所见，我已尝试制作 js，但仍然无法正常工作

我想问的是：

  • 我们如何从下拉菜单中获取值？
  • 我们如何从下拉列表中获取值作为整数，而不是字符串？

*抱歉英语不好

这是javascript

<script language="javascript">
function RadioCheck() {

var number = new Array('0', '20', '30', '40', '50', '60');
var selection1 = document.quiz.product1;
var selection2 = document.quiz.product2;
var amountselection1 = parseInt(document.quiz.amount1,10);
var amountselection2 = parseInt(document.quiz.amount2,10);

for (i=0; i<selection1.length; i++) {
if (selection1[i].checked == true) {
    result1=number[i]*amountselection1;
}
}

for (i=0; i<selection2.length; i++) {
if (selection2[i].checked == true) {
    result2=number[i]*amountselection2;
}
}


var result = (result1 + 'is the first result, and' + result2 + 'is the second result');
alert(result);
return false;
}

</script>

这是HTML

<form name="quiz">

<select id="product1">
<option name="product1" value="0" selected="selected"> </option>
<option name="product1" value="1">Product 1</option>
<option name="product1" value="2">Product 2</option>
<option name="product1" value="3">Product 3</option>
<option name="product1" value="4">Product 4</option>
<option name="product1" value="5">Product 5</option>
</select>

<select id="amount1">
<option name="amount1" value="0" selected="selected">0</option>
<option name="amount1" value="1">1</option>
<option name="amount1" value="2">2</option>
<option name="amount1" value="3">3</option>
<option name="amount1" value="4">4</option>
<option name="amount1" value="5">5</option>
</select>

<select id="product2">
<option name="product2" value="0" selected="selected"> </option>
<option name="product2" value="1">Product 1</option>
<option name="product2" value="2">Product 2</option>
<option name="product2" value="3">Product 3</option>
<option name="product2" value="4">Product 4</option>
<option name="product2" value="5">Product 5</option>
</select>

<select id="amount2">
<option name="amount2" value="0" selected="selected">0</option>
<option name="amount2" value="1">1</option>
<option name="amount2" value="2">2</option>
<option name="amount2" value="3">3</option>
<option name="amount2" value="4">4</option>
<option name="amount2" value="5">5</option>
</select>

<input type="submit" value="Check Answer" onClick="RadioCheck(); return false;">
</form>
4

2 回答 2

2

问题是你没有声明变量result1& result2。也为了得到数量选择使用document.quiz.amount1.value而不是仅仅document.quiz.amount1，等等amount2。再次比较下拉选择使用selection1[i].selected而不是selection1[i].checked.

试试这个代码：

function RadioCheck() {

  var number = new Array(0, 20, 30, 40, 50, 60); //quotes will work but not recommended for numbers
  var selection1 = document.quiz.product1;
  var selection2 = document.quiz.product2;
  var amountselection1 = parseInt(document.quiz.amount1.value, 10); //changed
  var amountselection2 = parseInt(document.quiz.amount2.value, 10); //changed
  var result1 = 0, result2 = 0; //added line

  for (i = 0; i < selection1.length; i++) {
    if (selection1[i].selected) { //changed
      result1 = number[i] * amountselection1;
    }
  }

  for (i = 0; i < selection2.length; i++) {
    if (selection2[i].selected) { //changed
      result2 = number[i] * amountselection2;
    }
  }


  var result = (result1 + 'is the first result, and ' + result2 + 'is the second result');
  alert(result);
  return false;
}
<form name="quiz">

  <select id="product1">
    <option name="product1" value="0" selected="selected"></option>
    <option name="product1" value="1">Product 1</option>
    <option name="product1" value="2">Product 2</option>
    <option name="product1" value="3">Product 3</option>
    <option name="product1" value="4">Product 4</option>
    <option name="product1" value="5">Product 5</option>
  </select>

  <select id="amount1">
    <option name="amount1" value="0" selected="selected">0</option>
    <option name="amount1" value="1">1</option>
    <option name="amount1" value="2">2</option>
    <option name="amount1" value="3">3</option>
    <option name="amount1" value="4">4</option>
    <option name="amount1" value="5">5</option>
  </select>

  <select id="product2">
    <option name="product2" value="0" selected="selected"></option>
    <option name="product2" value="1">Product 1</option>
    <option name="product2" value="2">Product 2</option>
    <option name="product2" value="3">Product 3</option>
    <option name="product2" value="4">Product 4</option>
    <option name="product2" value="5">Product 5</option>
  </select>

  <select id="amount2">
    <option name="amount2" value="0" selected="selected">0</option>
    <option name="amount2" value="1">1</option>
    <option name="amount2" value="2">2</option>
    <option name="amount2" value="3">3</option>
    <option name="amount2" value="4">4</option>
    <option name="amount2" value="5">5</option>
  </select>

  <input type="submit" value="Check Answer" onClick="RadioCheck(); return false;">
</form>

于 2016-02-16T22:55:25.803 回答
1

看起来这已经被回答了：Get selected value in dropdown list using JavaScript?

至于整数值而不是字符串，为什么不直接转换呢？parseInt($stringVal);

于 2012-06-10T02:17:32.437 回答