What is the most efficient way to deep clone an object in JavaScript?

David Y.

The Problem

What is the most efficient way to deep clone an object in JavaScript?

The Solution

Several methods for deep cloning objects in JavaScript have been invented over the years, with varying efficiency and effectiveness. Modern browsers provide the structuredClone() function, which will create a deep clone of an object provided to it using the structured clone algorithm. A code example:

const person = { firstName: "John", lastName: "Doe", age: 35, purchaseHistory: [ { productName: "apple", quantity: 5, datePurchased: new Date() }, { productName: "banana", quantity: 3, datePurchased: new Date() }, { productName: "pear", quantity: 4, datePurchased: new Date() } ] }; const clone = structuredClone(person); console.assert(clone !== person); // two distinct objects console.assert(clone.firstName === "John"); // same values

Note that structuredClone() does not support object properties that are functions or DOM nodes, and will throw a DataCloneError if these are found in the object provided for cloning.

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