6-11编程练习

个回答

Terry吳佳翰

2017-08-14 13:40:53

已采纳

<!DOCTYPE html>
<html>
<head>
   <title> 事件</title>
<script type="text/javascript">
   function count(){
     var a = '';
    //获取第一个输入框的值
    var txt1 = parseInt(document.getElementById("txt1").value);
   //获取第二个输入框的值
   var txt2 = parseInt(document.getElementById("txt2").value);
   //获取选择框的值
   var select = document.getElementById("select").value;

   switch(select){
        case "+":
           a = txt1 + txt2;
        break;
        case "-":
           a = txt1 - txt2;
        break;
        case "*":
           a = txt1 * txt2;
        break;
        case "/":
           a = txt1 / txt2;
   }
    //设置结果输入框的值
    document.getElementById("fruit").value = a;
   }
</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' />

</html>
0
爱上慕婉清6262634

2017-08-18 11:13:02

<!DOCTYPE html>
<html>
<head>
<title> 事件</title>
<script type="text/javascript">
   function count(){
    var txt1=Number(document.getElementById("txt1").value);
    var txt2=Number(document.getElementById("txt2").value);
   var sel=document.getElementById("select").value;
   var sum;
   if(sel=="+"){
        sum=txt1+txt2;
   }else if(sel=="-"){
        sum=txt1-txt2;
   }else if(sel=="*"){
        sum=txt1*txt2;
   }else if(sel=="/"){
        sum=txt1/txt2;
   }
   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();"/> 
   <input type='text' id='fruit' />
</body>
</html>

0