为什么这样的错误代码也可以通过啊？
明明就得不到正确结果
课程页地址：http://www.imooc.com/code/1488
<!DOCTYPE html>
<html>
<head>
<title> 事件</title>
<script type="text/javascript">
function count(){
var first = document.getElementById("txt1").value;
var sec = document.getElementById("txt2").value;
var result ;
//获取第一个输入框的值
//获取第二个输入框的值
//获取选择框的值
var selec = 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
if (select === "+"){
result = first + sec;
}
else if (select === "-" ){
result = first - sec;
}
else if (select ==="*"){
result = first * sec;
}
else if (select === "/")
{
result = first / sec;
}
//设置结果输入框的值
var theResult = document.getElementById("fruit");
theResult.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()" /> <!--通过 = 按钮来调用创建的函数，得到结果-->
<input type='text' id='fruit' />
</body>
</html>..
isu_腾飞浏览 1673回答 2
2回答
-
isu_腾飞
补充正确的代码如下：<!DOCTYPE html> <html> <head> <title> 事件</title> <script type="text/javascript"> function count(){ var first = parseInt(document.getElementById("txt1").value); var sec = parseInt(document.getElementById("txt2").value); var result = "" ; //获取第一个输入框的值 //获取第二个输入框的值 //获取选择框的值 var select = 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 if (select === "+"){ result = first + sec; } else if (select === "-" ){ result = first - sec; } else if (select ==="*"){ result = first * sec; } else if (select === "/") { result = first / sec; } //设置结果输入框的值 var theResult = document.getElementById("fruit"); theResult.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()" /> <!--通过 = 按钮来调用创建的函数，得到结果--> <input type='text' id='fruit' /> </body> </html>..
随时随地看视频慕课网APP
相关分类
JavaScript