Convert nested Javascript object to dot notation object

nested-object-to-dot-notation.js

const sample = {
    a: 1,
    b: {
        x: 2,
        y: 3,
        z: 4,
    },
    c: {
        x: 6,
        y: 7,
        z: {
            i: 8,
            j: 9,
            k: {
                foo: 10,
                bar: 11,
                extra: {
                    a: 12,
                    b: 13,
                }
            },
        },
    },
};

function flatObj(input, current) {
    const root = {};
    Object.keys(input).forEach(key => {
        const _key = current ? `${current}.${key}` : key;
        if (typeof input[key] !== 'object') {
            root[_key] = input[key]
        } else {
            Object.keys(input[key]).forEach(subkey => {
                if (typeof(input[key][subkey]) !== 'object') {
                    root[`${_key}.${subkey}`] = input[key][subkey];
                } else {
                    const children = flatObj(input[key][subkey], `${_key}.${subkey}`)
                    Object.assign(root, children)
                }
            })
        }
    });

    return root;
};

console.log(flatObj(sample))