JSON Deep Copy: All Methods Compared

The Deep Copy Problem

In JavaScript, objects are passed by reference. Assigning an object copies the reference, not the value. Deep copying creates a completely independent clone with no shared references.

Method 1: JSON.parse + JSON.stringify

const clone = JSON.parse(JSON.stringify(original));

Pros: No dependencies, fast for plain data.

Cons: Loses undefined, functions, Date objects (become strings), RegExp, Map, Set, BigInt. Throws on circular references.

Method 2: structuredClone (Modern)

const clone = structuredClone(original);

Pros: Built-in, handles Date, Map, Set, ArrayBuffer, circular references. No dependencies.

Cons: Drops functions and prototypes. Requires Node.js 17+ or modern browsers.

Method 3: Lodash cloneDeep

const _ = require('lodash');
const clone = _.cloneDeep(original);

Pros: Handles virtually everything including custom class instances.

Cons: Adds lodash as a dependency.

Comparison Table

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