How to Effectively Clone Arrays of Objects in JavaScript?

Cloning Arrays of Objects in JavaScript

Structure of Arrays

When cloning arrays of objects, it's crucial to consider the structure of the objects within the array and their relationships. If the objects reference other objects within the array, a shallow copy will only replicate the references, rather than creating new objects.

Available Solutions

There are several approaches to cloning arrays of objects in JavaScript, depending on the specific requirements:

1. StructuredClone (ES2021)

The structuredClone method is the most modern and efficient way to clone complex objects. It creates a deep copy, preserving the structure and relationships within the original array.

const clonedArray = structuredClone(originalArray);

2. JSON.parse

If the objects are serializable to JSON, you can convert them to a string using JSON.stringify and then parse them back to objects using JSON.parse. This approach does not work for non-serializable objects.

const clonedArray = JSON.parse(JSON.stringify(originalArray));

3. Spread Operator and Array.map

For shallow object cloning, you can use the spread operator ... within Array.map. This approach recreates the objects but does not create new references. It's efficient and only applicable to shallow objects.

const clonedArray = originalArray.map(obj => ({ ...obj }));

4. jQuery's Deep Copy

While jQuery's extend method can be used for shallow copying, a deep copy requires extend(true, {}, originalArray). However, this approach may encounter recursion issues.

Performance Considerations

The performance of cloning methods varies depending on the complexity and structure of the objects. structuredClone and spread operator are generally more efficient. Benchmark results for the example array in the provided Appendix show that spread operator is significantly faster than JSON.stringify, making it ideal for shallow object cloning.

Conclusion

The choice of cloning method depends on the specific requirements of the application. For deep cloning of complex object structures, structuredClone is recommended. For shallow cloning of serializable objects, JSON.stringify or the spread operator approach can be used.

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