与一个方法将origin转化为tree，要求支持无限级和性能

Answer 1

const originToTree = (origin) => {
    let tree = {}
    for (let key in origin) {
        if (key.includes('.')) {
            let keys = key.split('.')
            keys.reduce((pre, cur, index) => {
                if (index === keys.length - 1) {
                    pre[cur] = origin[key]
                } else {
                    if (pre[cur]) {
                        pre = pre[cur]
                    } else {
                        pre[cur] = {}
                        pre = pre[cur]
                    }

                }
                return pre
            }, tree)
        } else {
            tree[key] = origin[key]
        }
    }
    return tree
}