// structredCloneが遅いため
// SEE: http://var.blog.jp/archives/86038606.html
export function deepClone(x) {
    if (typeof x === "object") {
        if (x === null) return x;
        if (Array.isArray(x)) return x.map(deepClone);
        const obj = {};
        for (const [k, v] of Object.entries(x)){
            obj[k] = deepClone(v);
        }
        return obj;
    } else {
        return x;
    }
}