flat deep js object

flatObj.js

// https://gist.github.com/ichengzi/fa90fede6c7ce91bbb083ea2e5466a38

const entry = {
    a: {
        b: {
            c: {
                dd: "abcdd"
            }
        },
        d: {
            ee: "abdee"
        },
        f: 'af',
    }
};

// 递归写法， 深度优先， 所有叶子结点从左到右逐个打印
function flatObj1(obj, preKey = '', result = {}) {
    for (const key in obj) {
        if (obj.hasOwnProperty(key)) {
            if (typeof obj[key] === 'object') {
                flatObj1(obj[key], `${preKey}${key}.`, result);
            } else {
                result[`${preKey}${key}`] = obj[key];
            }
        }
    }
    return result;
}

// 迭代写法， 广度优先，叶子结点逐层从左向右打印；
// 所以输出顺序和递归方式不一样，如果有顺序要求，需要重新排序
function flatObj2(obj) {
    const result = {};
    const queue = Object.entries(obj);
    while (queue.length > 0) {
        const [key, value] = queue.shift();
        for (const [k, v] of Object.entries(value)) {
            if (typeof v === 'object') {
                queue.push([`${key}.${k}`, v]);
            } else {
                result[`${key}.${k}`] = v;
            }
        }
    }
    return result;
}

console.log(flatObj1(entry));
console.log(flatObj2(entry));