<!DOCTYPE html><html> <head> <title> 事件</title> <script type="text/javascript"> function count(){ var x=document.getElementById("txt1").value; var y=document.getElementById("txt2").value; var z=document.getElementById("select").value; var sum=""; switch(z){ case "+": sum=parseInt(x)+parseInt(y); break; case "-": sum=parseInt(x)-parseInt(y); break; case "*": sum=parseInt(x)*parseInt(y); break; default "/": sum=parseInt(x)/parseInt(y); } 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' /> </body></html>
3 回答
李晓健
TA贡献1036条经验 获得超461个赞
<!DOCTYPE html>
<html>
<head>
<title> 事件</title>
<script type="text/javascript">
function count(){
var x=document.getElementById("txt1").value;
var y=document.getElementById("txt2").value;
var z=document.getElementById("select").value;
var sum="";
switch(z){
case "+":
sum=parseInt(x)+parseInt(y);
break;
case "-":
sum=parseInt(x)-parseInt(y);
break;
case "*":
sum=parseInt(x)*parseInt(y);
break;
default:
sum=parseInt(x)/parseInt(y);
}
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' />
</body>
</html>default 后面是没有值的 就类似if(xxxx){}else{} 中的 else
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