GraphTar

tar.js

function containsRefs(array) {
    return array.length > 0 && (array[0] instanceof Object);
}


function makeRecord(node, records) {
    if (records.has(node)) {
        return records.get(node);
    }

    const record = {
        attrs: {},
        refs: {},
        id: records.size
    };

    records.set(node, record);

    for (let key in node) {
        const value = node[key];
        if (value instanceof Array && containsRefs(value)) {
            const array = [];
            for (let obj of value) {
                array.push(makeRecord(obj, records).id);
            }
            record.refs[key] = array;
        } else if (value instanceof Object) {
            record.refs[key] = makeRecord(value, records).id;
        } else {
            record.attrs[key] = value;
        }
    }
    return record;
}

function tar(node) {
    const records = new Map();
    const archive = {
        nodes: {}
    };
    const root = makeRecord(node, records);
    archive.root = root.id;

    for (let record of records.values()) {
        archive.nodes[record.id] = record;
        delete record.id;
    }
    return archive;
}

function untar(archive) {
    const nodes = {};
    for (let id in archive.nodes) {
        nodes[id] = archive.nodes[id].attrs;
    }
    for (let id in archive.nodes) {
        const node = nodes[id];
        const record = archive.nodes[id];

        for (let attr_name in record.refs) {
            const ref = record.refs[attr_name];
            if (ref instanceof Array) {
                const array = [];
                for (let item_ref of ref) {
                    const referent = nodes[item_ref];
                    array.push(referent);
                }
                node[attr_name] = array;
            } else {
                node[attr_name] = nodes[ref];
            }
        }
    }
    return nodes[archive.root];
}

const vasya = {name: "vasya", age: 25};
const petya = {name: "petya", age: 35};
const tolya = {name: "tolya", age: 17};

vasya.self = vasya;

vasya.friends = [petya, tolya];
petya.friends = [vasya, tolya];
tolya.friends = [vasya, petya];

let archive = tar(vasya);
console.log(JSON.stringify(archive));

vasya2 = untar(archive);
console.log(vasya2);