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请求大佬瞅一眼

<!DOCTYPE html>
<html>
<head>
<title> 事件</title>
<script type="text/javascript">
   function count(){
     var num1=document.getElementById("txt1").value;
    //获取第一个输入框的值
     var num2=document.getElementById("txt2").value;
//获取第二个输入框的值
//获取选择框的值
switch("select")
case '+':
     var result=num1+num2;
     break;
case '-':
     var result=num1-num2;
     break;
case '*':
     var result=num1*num2;
     break;
case '/':
     var result=num1/num2;
     break;
//获取通过下拉框来选择的值来改变加减乘除的运算法则
    document.getElementById("fruit").value=result;
    //设置结果输入框的值

   }
</script>
</head>
<body>
   <input type='text' id='txt1' />
   <select id='select'>
  <option value='+'>+</option>
  <option value="-">-</option>
  <option value="*">*</option>
  <option value="/">/</option>
   </select>
   <input type='text' id='txt2' />
   <input type='button' value=' = ' /> 
   <input type='text' id='fruit' />
</body>
</html>

慕圣5278473

2018-07-20

源自：JavaScript进阶篇 6-11

关注问题我要回答

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2 回答

聪叶
2018-07-25

function count(){

//获取第一个输入框的值

var txt1=document.getElementById("txt1").value;

//获取第二个输入框的值

var txt2=document.getElementById("txt2").value;

//获取选择框的值

var select=document.getElementById("select").value;

var fruit;

//获取通过下拉框来选择的值来改变加减乘除的运算法则

//设置结果输入框的值

switch(select){

case '+':

fruit=parseInt(txt1)+parseInt(txt2);

break;

case '-':

fruit=parseInt(txt1)-parseInt(txt2);

break;

case '*':

fruit=parseInt(txt1)*(txt2);

break;

case '/':

fruit=parseInt(txt1)/(txt2);

break;

}

document.getElementById('fruit').value=fruit;

}

0 回复有任何疑惑可以回复我~

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qq_旧城_7
2018-07-20

<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8">
<title> 事件</title>
<script type="text/javascript">
   function count(){

    //获取第一个输入框的值
    var num1 = document.getElementById("txt1").value;
   //获取第二个输入框的值
   var num2 = document.getElementById("txt2").value;
   //获取选择框的值
   var select1 = document.getElementById("select").value;
   //获取通过下拉框来选择的值来改变加减乘除的运算法则
   var result="";
   switch(select1){
        case "+":
           result = parseInt(num1)+ parseInt(num2);break;
        case "-": result = num1-num2;break;
        case "*": result = num1*num2;break;
        case "/": result = num1/num2;break;
   }
    //设置结果输入框的值
    document.getElementById("fruit").value=result;

   }
</script>
</head>
<body>
   <input type='text' id='txt1' />
   <select id='select'>
       <option value='+'>+</option>
       <option value="-">-</option>
       <option value="*">*</option>
       <option value="/">/</option>
   </select>
   <input type='text' id='txt2' />
   <input type='button' value=' = ' onclick="count()"; /> 
   <input type='text' id='fruit' />
</body>
</html><!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8">
<title> 事件</title>
<script type="text/javascript">
   function count(){

    //获取第一个输入框的值
    var num1 = document.getElementById("txt1").value;
   //获取第二个输入框的值
   var num2 = document.getElementById("txt2").value;
   //获取选择框的值
   var select1 = document.getElementById("select").value;
   //获取通过下拉框来选择的值来改变加减乘除的运算法则
   var result="";
   switch(select1){
        case "+":
           result = parseInt(num1)+ parseInt(num2);break;
        case "-": result = num1-num2;break;
        case "*": result = num1*num2;break;
        case "/": result = num1/num2;break;
   }
    //设置结果输入框的值
    document.getElementById("fruit").value=result;

   }
</script>
</head>
<body>
   <input type='text' id='txt1' />
   <select id='select'>
       <option value='+'>+</option>
       <option value="-">-</option>
       <option value="*">*</option>
       <option value="/">/</option>
   </select>
   <input type='text' id='txt2' />
   <input type='button' value=' = ' onclick="count()"; /> 
   <input type='text' id='fruit' />
</body>
</html>