Adding Support for _.cloneDeep using recursiveClone

[zargold]

Supports _.cloneDeep as discussed in Issue: #121.

• Tests written
• Documentation updated
• added support per Object.fromEntries on MDN.

[VitorLuizC]

It would break if we pass null.

[iandrewt]

This breaks on an object with circular references

const object = {
  'bar': {},
  'foo': { 'b': { 'c': { 'd': {} } } },
};

object.foo.b.c.d = object;
object.bar.b = object.foo.b;

cloneDeep(object);

Uncaught RangeError: Maximum call stack size exceeded

[iandrewt]

Here's the cloneDeep function I'm using, courtesy of StackOverflow

function cloneDeep(obj, hash = new WeakMap()) {
  if (Object(obj) !== obj || obj instanceof Function) {
    return obj;
  }

  if (hash.has(obj)) {
    return hash.get(obj);
  }

  let result: any;

  try { // Try to run constructor without arguments
    result = new obj.constructor();
  } catch (e) {
    result = Object.create(Object.getPrototypeOf(obj));
  }

  if (obj instanceof Map) {
    Array.from(obj, ([key, val]) => result.set(cloneDeep(key, hash), cloneDeep(val, hash)));
  } else if (obj instanceof Set) {
    Array.from(obj, (key) => result.add(cloneDeep(key, hash)));
  }

  hash.set(obj, result);

  return Object.assign(result, ...Object.keys(obj).map(key => ({ [key]: cloneDeep(obj[key], hash) })));
};

[zargold]

Here's the cloneDeep function I'm using, courtesy of StackOverflow

function cloneDeep(obj, hash = new WeakMap()) {
  if (Object(obj) !== obj || obj instanceof Function) {
    return obj;
  }

  if (hash.has(obj)) {
    return hash.get(obj);
  }

  let result: any;

  try { // Try to run constructor without arguments
    result = new obj.constructor();
  } catch (e) {
    result = Object.create(Object.getPrototypeOf(obj));
  }

  if (obj instanceof Map) {
    Array.from(obj, ([key, val]) => result.set(cloneDeep(key, hash), cloneDeep(val, hash)));
  } else if (obj instanceof Set) {
    Array.from(obj, (key) => result.add(cloneDeep(key, hash)));
  }

  hash.set(obj, result);

  return Object.assign(result, ...Object.keys(obj).map(key => ({ [key]: cloneDeep(obj[key], hash) })));
};

Yes, if you care about this very unusual use case (that I've never used in 7 years of development). Very rarely do even libraries use this pattern of circular references then you could use a modified version as you quoted, but I doubt more than 1% of people will need that.

Just in case we want to support that: recursiveCloneWithCircularReference it would be easy:

const recursiveClone = (src, hash = new WeakMap()) => {

      if (src === null || typeof src !== 'object') { // for primitives / functions / non-references/pointers
        return src
      }
     if (hash.has(obj)) {
        return hash.get(obj);
      }
     let result;
      if (Array.isArray(src)) { // for arrays
        result = src.map(element => recursiveClone(element, hash))
      }
      result = Object.fromEntries(
        Object.entries(src).map(
          ([key, val]) => ([key, recursiveClone(val, hash)])
        )
      )
      hash.set(src, result);
      return result;
    }

In case we also want to support things like Maps & Sets we could too.

[iandrewt]

Unfortunately the project I was working on did need all the edge cases, but I'm glad there's a good simplified version

[kingyue737]

Is structuredClone equal to deepClone?
https://developer.mozilla.org/en-US/docs/Web/API/structuredClone

[zargold]

Is structuredClone equal to deepClone?
https://developer.mozilla.org/en-US/docs/Web/API/structuredClone

Awesome find. I think people may complain that it lacks support for functions, but I don't often see the need for that piece of functionality.