put_in_object

const putAt = (path, obj, value) => {
  const ObjCopy = {...obj};
  const arrPath = path.split('.').reverse();
  
  const copy = arrPath.reduce((acc, name, i) => {
    const temp = {};
    if(i === 0) {
      temp[name] = value;
    } else {
      temp[name] = {...acc};
    }
    return {...temp};
  }, ObjCopy)
  return {...ObjCopy, ...copy};
}

console.log('putted:', putAt('a.b.c', {d: ''}, 'good!'));