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输出没反应，求解答

来源：6-11 编程练习

慕前端7075531

2022-08-17 14:40

<!DOCTYPE html>

<html>

<head>

function count() {

//获取第一个输入框的值

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

//获取第二个输入框的值

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

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

//获取选择框的值

var result="";

switch (c) {

case "+":

result = a + b;

break;

case "-":

result = a - b;

break;

case "*":

result = a * b;

break;

case "/":

result = a / b;

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

//设置结果输入框的值

document.getElementById("fruit").value = result;

}

</script>

</head>

<body>

</select>

</body>

</html>

写回答关注

5回答

慕函数7131464

2023-03-02 22:47:12

var c = parseInt(document.getElementById("select").value);
改成var c = document.getElementById("select").value;

0 1
qq_慕哥0499155

2022-10-18 21:46:58

或者是加减符合那里不设置parseInt

0 0
qq_慕虎4260202

2022-09-26 20:33:24

<!DOCTYPE html>
<html>
<head>
<title> 事件</title>
<script type="text/javascript">
   function count(){
      var s=document.getElementById("txt1").value;
    //获取第一个输入框的值
    var b=document.getElementById("txt2").value;
   //获取第二个输入框的值
   //获取选择框的值
   var f=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
    switch(f){
       case "+":document.getElementById('fruit').value=s+b;
       break;
       case "-":document.getElementById('fruit').value=s-b;
       break;
       case "*":document.getElementById('fruit').value=s*b;
       break;
       case "/":document.getElementById('fruit').value=s/b;
       break;
       default:
           document.getElementById('fruit').value=111;
   }
    //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=' = ' onclick="count()"/> 
   <input type='text' id='fruit' />
</body>
</html>

1 0

qq_慕哥0...

要调用函数，在body那里调用onclick="count()"，不调用函数在里面写多少都没用

2022-10-18 21:42:27

共 1 条回复 >
老佛虫

2022-08-25 11:33:30

<!DOCTYPE html>
<html>
<head>
<title> 事件</title>
<script type="text/javascript">
function count(){
num1=parseInt(document.getElementById("txt1").value);
num2=document.getElementById("select").value;
num3=parseInt(document.getElementById("txt2").value);
switch (num2){
case "+":
num4=num1+num3;
break;
case "-":
num4=num1-num3;
break;
case "*":
num4=num1*num3;
break;
case "/":
num4=num1/num3;
break;
default:
num4=11111;
}
document.getElementById("fruit").value = num4;

}
</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>

0 0
普增林

2022-08-18 15:35:33

<!DOCTYPE html>

<html>

<head>

<title>事件</title>

<script type="text/javascript">

function count() {

//获取第一个输入框的值

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

//获取第二个输入框的值

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

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

//获取选择框的值

var result;

switch (c) {

case "+":

result = a + b;

break;

case "-":

result = a - b;

break;

case "*":

result = a * b;

break;

case "/":

result = a / b;

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

//设置结果输入框的值

console.log(a,b,c,result);

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>

0 1