switch方法中使用数字区间

function getCategory(age) {
    var category = "";
    switch (true) {
        case isNaN(age):
            category = "not an age";
            break;
        case (age >= 50):
            category = "Old";
            break;
        case (age <= 20):
            category = "Baby";
            break;
        default:
            category = "Young";
            break;
    };
    return category;
}
getCategory(5);  // 将返回 "Baby"