SOURCE

const obj = {
    a:1,
    b:2,
    c:{
        d:3
    }
}

const obj1 = JSON.parse(JSON.stringify(obj));
function deep(obj){
    const newobj = {}
    for(let key in obj){
        if(typeof obj[key] === 'object'){
            newobj[key] = deep(obj[key])
        }else{
            newobj[key] = obj[key]
        }
    }
    return newobj
}
obj.c.d = 5;
console.log(obj)
console.log(obj1)
console.log(deep(obj))