More comprehensive deepclone with JS. Cover null and Array.

betterDeepClone.js

/**
 * You should be good with this solution
 * More comprehensive deepclone with JS. Cover null and Array.
 * Problems:
 * 1. did not solve the circular dependency
 * @param {Object} sourceObj
 * @returns
 */
var deepCloneBetter = (sourceObj) => {
  // if we are not dealing with complex data structure
  if (typeof sourceObj !== 'object' && sourceObj !== null) {
    return sourceObj;
  }
  let result = Array.isArray(sourceObj) ? [] : {};
  for (let key in sourceObj) {
    //ignore the prototype chain
    if (Object.prototype.hasOwnProperty.call(sourceObj, key)) {
      if (typeof sourceObj[key] !== 'object' && sourceObj[key] !== null) {
        result[key] = deepCloneBetter(sourceObj[key]);
      } else {
        result[key] = sourceObj[key];
      }
    }
  }
  return result;
};

// more elegant version with Functional programming with 30s javascript version

const deepClone = (obj) => {
  let clone = Object.assign({}, obj);
  Object.keys(clone).forEach(
    (key) =>
      (clone[key] =
        typeof obj[key] === 'object' ? deepClone(obj[key]) : obj[key]),
  );
  return Array.isArray(obj) && obj.length
    ? (clone.length = obj.length) && Array.from(clone)
    : Array.isArray(obj)
    ? Array.from(obj)
    : clone;
};