Let's dive into the world of JavaScript microbenchmarks!

Benchmark Definition JSON

The provided JSON represents a benchmark test case that compares three different methods for creating a copy of an object in JavaScript: _.cloneDeep from Lodash, _.clone, and the spread operator (...). The benchmark aims to measure which method is the fastest.

Script Preparation Code

The script preparation code creates a sample object MyObject with properties description, myNumber, and myBoolean. This object will be used as the source of truth for creating copies.

var MyObject = {
  description: 'a',
  myNumber: 123456789,
  myBoolean: true
};

var myCopy = null;

Html Preparation Code

The HTML preparation code includes a reference to the Lodash library, which will be used in the benchmark tests.

<script src='https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.5/lodash.min.js'></script>

Individual Test Cases

There are three test cases:

1. Lodash cloneDeep: This test case uses Lodash's cloneDeep function to create a deep copy of MyObject.
2. Lodash clone: This test case uses Lodash's clone function to create a shallow copy of MyObject.
3. Spread operator: This test case uses the spread operator (...) to create a new object with the same properties as MyObject.

Library: Lodash

Lodash is a popular JavaScript utility library that provides a wide range of functions for working with arrays, objects, and more. The cloneDeep and clone functions are used in this benchmark to create copies of objects.

The cloneDeep function creates a deep copy of an object, meaning it recursively clones all nested properties. This is useful when you need to preserve the entire structure of an object.

The clone function creates a shallow copy of an object, meaning it only copies the top-level properties and does not recurse into nested objects. This can be faster than cloneDeep, but may not be suitable for all use cases.

Special JS Feature: Rest Operator (Spread Operator)

The spread operator (...) is a modern JavaScript feature introduced in ECMAScript 2015. It allows you to create a new object with the same properties as an existing object, without modifying the original.

In this benchmark, the spread operator is used to create a copy of MyObject. This approach can be fast and memory-efficient, but may not preserve the entire structure of the object if it contains nested objects or complex data structures.

Pros and Cons

Here's a brief summary of each approach:

• Lodash cloneDeep: Pros:

  • Preserves the entire structure of the object.
  • Can be useful when working with complex data structures.
  • Provides a simple and consistent way to create deep copies.

• Cons:

  • Can be slower than other approaches due to recursion.
  • May not be suitable for very large objects or performance-critical applications.

• Lodash clone: Pros:

  • Faster than cloneDeep due to shallow copying.
  • Suitable for most use cases that don't require deep copying.

• Cons:

  • Does not preserve the entire structure of the object.
  • May not be suitable for complex data structures or performance-critical applications.

• Spread operator: Pros:

  • Fast and memory-efficient.
  • Preserves the top-level properties of the original object.
  • Suitable for most use cases that don't require deep copying.

• Cons:

  • Does not preserve nested objects or complex data structures.
  • May not be suitable for very large objects or performance-critical applications.

Other Alternatives

There are several other approaches to creating copies of objects in JavaScript, including:

1. Object.assign(): This method creates a shallow copy of an object by assigning the values from another object to new properties.
2. JSON.parse(JSON.stringify(obj)): This approach creates a deep copy of an object by serializing it as JSON and then parsing it back into an object.
3. Array.prototype.slice.call(obj): This approach creates a shallow copy of an array-like object.

Each approach has its own trade-offs, and the choice ultimately depends on the specific use case and requirements.