Lodash _.cloneDeepWith() method

Intermediate
⏱️ 7 min read
📚 Updated: May 2026
🎯 3 Code examples
🚀 3 Try-it labs
Lodash

What you’ll learn

  • How _.cloneDeepWith(value, customizer) deep-clones while letting you override specific nodes.
  • When to return a replacement value versus undefined for default cloning.
  • How this differs from _.cloneDeep() and shallow _.cloneWith().
  • Practical patterns for functions, classes, or application-specific objects.

Prerequisites

Read _.cloneDeep() first so the recursive cloning baseline is clear.

  • You understand JavaScript references and nested object graphs.
  • You can run snippets in Node or open Try-it labs in the browser.

Overview

_.cloneDeepWith is cloneDeep plus a per-node hook. Use it when some nested values should not use default cloning (for example shared functions, markers, or wrapped instances).

Per-node control

Inspect each visited value and decide whether to substitute or defer to Lodash.

undefined means default

Return nothing to keep normal recursive cloning for that branch.

Power with cost

Customizers add CPU work per node—keep logic small and predictable.

Syntax

javascript
_.cloneDeepWith(value, [customizer])
  • value: the root value to clone deeply.
  • customizer: invoked for each node; return a replacement or undefined for default cloning.
  • Returns: the cloned value produced by the merge of defaults and your overrides.
1

Reuse function references

Return the same function instance instead of letting Lodash walk it as an object.

javascript
import cloneDeepWith from "lodash/cloneDeepWith";

var id = function (x) { return x; };
var source = { scale: 2, fn: id };
var copy = cloneDeepWith(source, function (value) {
  if (typeof value === "function") {
    return value;
  }
});

console.log(copy.fn === source.fn); // true
Try it Yourself
2

Replace a nested leaf

Return an explicit clone for a nested object while other fields use defaults.

javascript
import cloneDeepWith from "lodash/cloneDeepWith";

var source = {
  label: "root",
  node: { id: 1, tag: "leaf" }
};
var copy = cloneDeepWith(source, function (value, key) {
  if (key === "node" && value && typeof value === "object") {
    return { id: value.id, tag: value.tag.toUpperCase() };
  }
});

console.log(copy.node.tag); // "LEAF"
Try it Yourself
3

Fallback to default cloning

Return nothing for primitives so Lodash keeps normal deep clone behavior.

javascript
import cloneDeepWith from "lodash/cloneDeepWith";

var source = { a: 1, b: { c: 2 } };
var copy = cloneDeepWith(source, function (value) {
  if (typeof value === "number" && value === 1) {
    return 100; // override this leaf
  }
  // undefined → lodash default for everything else
});

console.log(copy.a, copy.b.c);
Try it Yourself

📋 cloneDeepWith vs related APIs

MethodDepthCustomizer
_.cloneDeepWith(value, fn)DeepYes, per node
_.cloneDeep(value)DeepNo
_.cloneWith(value, fn)ShallowYes, top level

Pitfalls to avoid

Perf

Heavy customizers

The function runs often while traversing large trees—avoid expensive work per call.

Logic

Wrong key checks

Customizer keys differ for arrays versus objects; verify behavior on sample data.

Sharing

Accidental shared refs

Returning the original nested object keeps aliasing—only do this intentionally.

❓ FAQ

If you return a value, Lodash uses it as the cloned result for that node. If you return undefined, Lodash falls back to default deep cloning for that value.
Usually yes, because the customizer runs for visited nodes. Keep the function cheap.
No. It builds a new structure based on cloning rules and your customizer.
cloneWith is shallow with a customizer. cloneDeepWith recurses through nested structures with the same hook pattern.

Summary

  • Purpose: deep clone with selective overrides via customizer.
  • Rule: return a value to substitute a node; return undefined for default cloning.
  • Next: Lodash _.cloneWith().
Did you know?

Returning undefined from the customizer tells Lodash to apply its default cloning logic for that node.

About the author

Mari Selvan M P
Mari Selvan M P 🔗

Developer, cloud engineer, and technical writer

  • Experience 12 years building web and cloud systems
  • Focus Full Stack Development, AWS, and Developer Education

I write practical tutorials so students and working developers can learn by doing—from databases and APIs to deployment on AWS.

AWS Certified Developer – Associate (Credly)

6 people found this page helpful

Lodash _.cloneDeep() Lodash _.cloneWith()