四则运算

<script>
    var num1 = parseFloat(prompt('请输入第一个数'));
    var num2 = parseFloat(prompt('请输入第二个数'));
    var fuhao = prompt('请输入运算符号');
    switch (fuhao) {
        case "+":
            //var sum = num1+num2;
            alert('两数的运算结果是' + num1 + fuhao + num2 + '=' + (num1 + num2));
            break;
        case "-":
            alert('两数的运算结果是' + num1 + fuhao + num2 + '=' + num1 - num2);
            break;
        case "*":
            alert('两数的运算结果是' + num1 + fuhao + num2 + '=' + (num1 * num2));
            break;
        case "/":
            alert('两数的运算结果是' + num1 + fuhao + num2 + '=' + (num1 / num2));
            break;
        default:
            alert('你输入的运算符号有误');
            break;
    }
</script>