Question

让我建立了一个简单表单的客户端进行基本计算。有6个下降都包含N / A，1,2,3。最后，从这些下降计算总体平均值。客户端想要完全忽略包含N / A的任何下降，这意味着如果N / A在6个下降中的2个中，那么平均值应该仅在4个下降时计算。如果用户选择了N / A，我只是迷失了逻辑或if语句需要告诉总字段忽略某个下拉字段。这是我的代码，不起作用。请提出一些想法。

<html>
<head><script type="text/javascript">
var aFieldNames = new Array();
aFieldNames["N/A"]=0;
aFieldNames["1"]=1;
aFieldNames["2"]=2;
aFieldNames["3"]=3;
var nCount = 0;
var nSum = 0;
event.value = 0;
for(i = 0; i < aFieldNames.length; i++)
{
if(this.getField(aFieldNames[i]).valueAsString != "N/A") 
{
nCount++;
nSum += parseFloat(this.getField(aFieldNames[i]).value);
}
}
if(nCount != 0) 
 {
event.getElementById("bpover").value = nSum / nCount;
 }
</script>
</head>
<body>
<select name="Value[]" onChange="alert(this.value):">
 <option name="N/A">N/A</option>
  <option name="1">1</option>
   <option name="2">2</option>
    <option name="3">3</option>
  </select><br>
   <select name="Value[]" onChange="alert(this.value):">
  <option name="N/A">N/A</option>
   <option name="1">1</option>
   <option name="2">2</option>
   <option name="3">3</option>
   </select><br>
    <select name="Value[]" onChange="alert(this.value):">
   <option name="N/A">N/A</option>
   <option name="1">1</option>
    <option name="2">2</option>
    <option name="3">3</option>
    </select><br>
     <select name="Value[]" onChange="alert(this.value):">
   <option name="N/A">N/A</option>
    <option name="1">1</option>
    <option name="2">2</option>
    <option name="3">3</option>
    </select><br>
    <select name="Value[]" onChange="alert(this.value):">
   <option name="N/A">N/A</option>
   <option name="1">1</option>
    <option name="2">2</option>
     <option name="3">3</option>
    </select><br>
    <br>
   avg <input type="text" name="Average" ID="bpover" readonly>
    </body>
    </html>

Answer 1

<强>首先

在你的陈述中：

<select name="Value[]" onChange="alert(this.value):">

您正在使用无用的：而是使用; 。

<强>第二

该方法应循环遍历所有选择框。
读取没有N / A作为值的选择框的值
使用parseFloat()或parseInt()将获得的值转换为数字来计算平均值。
显示

请参阅以下代码：

<script>
function calculateAverage()
{
  var boxes = document.getElementsByTagName('select')
  var nSum = 0;
  var nCount = 0;
  event.value = 0;
  for(var i=0; i<boxes.length;i++)
  {
  	if(boxes[i].value != "N/A")
    {
    	alert(boxes[i].value);
    	nSum += parseFloat(boxes[i].value);
      nCount++;
    }
  }
  var avg = nSum/nCount;
  document.getElementById('bpover').value = avg;
}
</script>

<select name="Value[]" onChange="alert(this.value);">
 <option name="N/A">N/A</option>
  <option name="1">1</option>
   <option name="2">2</option>
    <option name="3">3</option>
  </select><br>
   <select name="Value[]" onChange="alert(this.value);">
  <option name="N/A">N/A</option>
   <option name="1">1</option>
   <option name="2">2</option>
   <option name="3">3</option>
   </select><br>
    <select name="Value[]" onChange="alert(this.value);">
   <option name="N/A">N/A</option>
   <option name="1">1</option>
    <option name="2">2</option>
    <option name="3">3</option>
    </select><br>
     <select name="Value[]" onChange="alert(this.value);">
   <option name="N/A">N/A</option>
    <option name="1">1</option>
    <option name="2">2</option>
    <option name="3">3</option>
    </select><br>
    <select name="Value[]" onChange="alert(this.value);">
   <option name="N/A">N/A</option>
   <option name="1">1</option>
    <option name="2">2</option>
     <option name="3">3</option>
    </select><br>
    <br>
    <button onClick="calculateAverage()">
    Calculate
    </button>
    
   avg <input type="text" name="Average" ID="bpover" readonly>

Answer 2

你走了！ @Shakti Phartiyal的答案解释了错误的事情。

function calcAvg(){
  //Get all elements with 'class="select"'
  var selects = document.getElementsByClassName("select");
  //Initialize vars
  var avg = 0;
  var count = 0;
  //Calculate average
  for(var i=0;i<selects.length;i++){
    if(selects[i].value!="N/A"){
      count++;
      avg+=Number(selects[i].value);
      //Alert for debugging purposes
      //alert(selects[i].value+" "+avg);
    }
  }
  avg=avg/count;
  //Output average
  document.getElementById("bpover").value=avg;
}

<select class="select" name="Value[]" onChange="calcAvg();">
 <option name="N/A">N/A</option>
  <option name="1">1</option>
   <option name="2">2</option>
    <option name="3">3</option>
  </select><br>
   <select class="select" name="Value[]" onChange="calcAvg();">
  <option name="N/A">N/A</option>
   <option name="1">1</option>
   <option name="2">2</option>
   <option name="3">3</option>
   </select><br>
    <select class="select" name="Value[]" onChange="calcAvg();">
   <option name="N/A">N/A</option>
   <option name="1">1</option>
    <option name="2">2</option>
    <option name="3">3</option>
    </select><br>
     <select class="select" name="Value[]" onChange="calcAvg();">
   <option name="N/A">N/A</option>
    <option name="1">1</option>
    <option name="2">2</option>
    <option name="3">3</option>
    </select><br>
    <select class="select" name="Value[]" onChange="calcAvg();">
   <option name="N/A">N/A</option>
   <option name="1">1</option>
    <option name="2">2</option>
     <option name="3">3</option>
    </select><br>
    <br>
   avg <input type="text" name="Average" id="bpover" readonly>

如何从下拉列表中计算平均值，不包括“N / A”值

2 个答案: