有大佬吗，救救孩子，运行不了

源自：6-11 编程练习

<!DOCTYPE html>

<html>

<head>

function count(){

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

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

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

var txt3 = "";

switch(info){

case:'+':

txt3 = parseFloat(txt1)+parseFloat(txt2);

break;

case:'-':

txt3 = parseFloat(txt1)-parseFloat(txt2);

break;

case:'*':

txt3 = parseFloat(txt1)*parseFloat(txt2);

break;

case:"/":

txt3 = parseFloat(txt1)/parseFloat(txt2);

break;

default:

document.write("无此功能");

break;

} //获取通过下拉框来选择的值来改变加减乘除的运算法则

document.getElementById('fruit').value = txt3; //设置结果输入框的值

}

</script>

</head>

<body>

</select>

</body>

</html>

提问者：qq_慕沐3366631 2019-08-12 16:03