Object.keys(obj).forEach making deep copy of object js

Question

I need to write a function for deep copying of objects. I have wrote one, but it doesn't work. Could anyone help me to fix it? thanks in advance! const cloneObj = {};

    function makeObjectDeepCopy2(obj, cloneObj) {

        Object.keys(obj).forEach((key) => {
            if (obj[key] instanceof Object) {
                cloneObj[key] = makeObjectDeepCopy2(obj[key], cloneObj[key]);
            }
            cloneObj[key] = obj[key];
            return cloneObj;
        });
    }

    var a = {
        a: 5,
        b: { g: 8, y: 9, t: { q: 48 } },
        x: 47,
        l: { f: 85, p: { u: 89, m: 7 }, s: 71 },
        r: { h: 9, a: 'test', s: 'test2' }
    };

    makeObjectDeepCopy2(a, cloneObj);
    console.log(cloneObj);
    console.log(a);