跟标准答案对照了几遍，为啥还是输出不了

源自：6-11 编程练习

<!DOCTYPE html>

<html>

<head>

function count(){

var a = parseInt (document.getElementById("txt1").value); //获取第一个输入框的值

var b = parseInt (document.getElementById("txt2").value); //获取第二个输入框的值

var c = document.getElementById("select").value; //获取选择框的值

var d = "" ; //获取通过下拉框来选择的值来改变加减乘除的运算法则

switch( c )

{

case "+":

d = a + b;

break;

case "-" :

d = a - b;

break;

case "*";

d = a * b;

break;

case "/"

d = a / b;

break;

}

document.getElementById('fruit').value = d //设置结果输入框的值

}

</script>

</head>

<body>

</select>

</body>

</html>

提问者：慕桂英3019087 2018-07-27 00:39