clone.js

const clone = obj => {
  const typeOf = o => 
    ({}).toString.call(o).match(/\[object (\w+)\]/)[1];
  if(typeOf(obj) !== 'Object')
    throw new TypeError('must be an object');
  var out = {};
  for(let attr in obj){
    const item = obj[attr];
    switch(typeOf(item)){
      case 'Number':
      case 'String':
        out[attr] = item;
        break;
      case 'Function':
        out[attr] = item.bind(null);
        break;
      case 'Array':
        out[attr] = item.map(x => x)
        break;
      case 'Object':
        out[attr] = clone(item);
        break;
    }
  }
  return out;
};


const obj = {
  a: 1,
  b: 2,
  str: 'hello',
  arr: [1,3,4,6,,7],
  fn: (a, b) => a + b
}

const newOne = clone(obj);

console.log(newOne, newOne === obj);