switchcase的用法

<script>
    var level = prompt("请输入员工评级");
    var salary = 5000;
    switch (level) {
        case "A":
            salary = salary + 500;
            console.log('哈哈哈' + salary);
            break;
        case "B":
            salary = salary + 200;
            console.log('不不不');
            break;
        case "C":
            break;
        case "D":
            salary = salary - 200;
            break;
        case "E":
            salary = salary - 500;
            break;
        default:
            alert("请按套路出牌，输入A-E的值");
            break;
    }
    console.log(salary);
</script>