<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<title> 事件</title>
<script type="text/javascript">
function count(){
var a=parseInt(document.getElementById("txt1").value;);
var b=parseInt(document.getElementById("txt2").value;);
var box=document.getElementById("select").value;
var sum;
switch(box){
case "+":
sum=a+b;
return sum;
break;
case "-":
sum=a-b;
return sum;
break;
case "*":
sum=a*b;
return sum;
break;
case "/":
sum=a/b;
return sum;
break;
};
document.getElementById("fruit").value=sum;
};
</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()"/> <!--通过 = 按钮来调用创建的函数，得到结果-->
<input type='text' id="fruit" value=""/>
</body>
</html>
1 回答
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慕用0418482
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<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<title> 事件</title>
<script type="text/javascript">
function count(){
var a=parseInt(document.getElementById("txt1").value);
var b=parseInt(document.getElementById("txt2").value);
var box=document.getElementById("select").value;
var sum;
switch(box){
case "+": sum=a+b ; break;
case "-": sum=a-b ; break;
case "*": sum=a*b ; break;
case "/": sum=a/b ; break;
};
document.getElementById("fruit").value=sum;
console.log(sum)
};
</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()"/> <!--通过 = 按钮来调用创建的函数，得到结果-->
<input type='text' id="fruit" value=""/>
</body>
</html>不用return
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