3.6.5 深度复制

function deepcopy(source) {
    let result = source instanceof Array ? [] : {};
    let t = null;
    for (let key in source) {
        t = typeof(source[key]);
        if (key === "reply") {
            console.log(t);
        }
        result[key] = t === "object" ? deepcopy(source[key]): source[key];
    }
    return result;
}