<script type="text/javascript">
function count(){
//获取第一个输入框的值
var t1 = document.getElementById("txt1").value
//获取第二个输入框的值
var t2 = document.getElementById("txt2").value
//获取选择框的值
var sel = 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
var jg;
switch(sel){
case '+':
var jia = t1+t2
jg = jia
break;
case '-':
var jian = t1-t2
jg = jian
break;
case '*':
var cheng = t1*t2
jg = cheng
break;
case '/':
var chu = t1/t2
jg = chu
break;
default:
alert("请输入适当的数据")
}
//设置结果输入框的值
document.getElementById("fruit").value = jg;
}
</script>
