我的显示不出来-慕课网

我的显示不出来

来源：6-11 编程练习

慕先生5537848

2017-06-13 20:57

<!DOCTYPE html>
<html>
<head>
<title> 事件</title>
<script type="text/javascript">
   function count()
   {
    var text_1=document.getElementById("txt1").value;
    text_1=parseInt(text_1);
var text_2=document.getElementById("txt2").value;
text_2=parseInt(text_2);
var result;
var p=document.getElementById("select").value;
switch(p)
{
     case "+" :
         result=text_1+text_2;
         break;
     case "-" :
         result=text_1-text_2;
         break;
    case "*" :
        result=text_1*text_2;
        break;
    case "/" :
         result=text_1/text_2;
         break;
         default;
}
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 name="button" type="button" onClick="count()" value="=" />
   <input type='text' id='fruit' />
</body>
</html>