JavaScript简单计算器代码：
<input type="text" id="number1" placeholder="请输入第一个数
字"/><br/>
<input type="text" id="opt" placeholder="请输入操作符"/><br/>
<input type="text" id="number2"
placeholder="请输入第二个数字"/><br/>
<input type="button" value="计算" onclick="jisuan()" /><br/>
<span id="resultshow"></span>
function jisuan(){
var number1 = document.getElementById("number1").value;
var opt = document.getElementById("opt").value;
var number2 = document.getElementById("number2").value;
if(isNaN(menubar1) || isNaN(number2)){
alert("请输入数字");
return ;
}
number1 = Number(number1);
number2 = Number(number2)
var result = 0;
switch (opt){
case "+":
result = number1 + number2;
break;
case "-":
result = number1 - number2;
break;
case "*":
result = number1 * number2;
break;
case "/":
if (number2==0){
alert("除数不能为0")
}else{
result = number1 / number2;
}
break;
default:
result = 0;
}
result = result.toFixed(2);
document.getElementById("resultshow").innerText=result;
}
