function?count(){
???????
????//獲取第一個輸入框的值
????var?num1=parseInt(document.getElementById("txt1").value);
????//獲取第二個輸入框的值????
????var?num2=parseInt(document.getElementById("txt2").value);
????//獲取選擇框的值
????var?oper?=?document.getElementById("select").value;
????//獲取通過下拉框來選擇的值來改變加減乘除的運算法則
????var?result;
????switch(oper)
????{
????????case?"+":
????????????result=num1+sum2;
????????????break;
????????case?"-":
????????????result=num1-sum2;
????????????break;
????????case?"*":
????????????result=num1*sum2;
????????????break;
????????case?"/":
????????????result=num1/sum2;
????????????break;
????????default:break;
????}
????
????//設置結(jié)果輸入框的值?
???
????document.getElementById("fruit").value=result;
????
???}