Let's dive into the world of JavaScript microbenchmarks on MeasureThat.net.

Benchmark Definition

The benchmark tests two approaches to assign values to an object:

1. Using lodash.assign()
2. Using the spread operator (...)

Script Preparation Code

The script preparation code defines a variable person with a nested object:

var person = {name: 'Frederick', lastName: 'Corcino Alejo'};

This setup is used as the source data for both benchmark definitions.

Html Preparation Code

An external library, lodash.js, is loaded via an HTML script tag to make the lodash.assign() function available:

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

Individual Test Cases

There are two test cases:

1. Lodash: The benchmark definition uses _.assign() to create a copied object from person and the new age object:

let age = {age: 15};
let copied = _.assign({}, person, age);

2. Native: The benchmark definition uses the spread operator (...) to create a copied object from person and the new age object:

let age = {age: 15};
let copied = {...person, ...age};

Pros and Cons of Each Approach

1. Lodash (.assign()):
   • Pros:
     • More explicit and readable code.
     • Less error-prone since it's a function with clear input/output expectations.
   • Cons:
     • Requires an external library (lodash.js).
     • Might be slower due to the overhead of calling an external function.
2. Native (Spread Operator):
   • Pros:
     • Faster execution since it's a built-in JavaScript feature.
     • More concise and expressive code.
   • Cons:
     • Might be less readable for developers unfamiliar with the spread operator.
     • Error-prone if not used correctly.

Library: Lodash

Lodash is a popular utility library for JavaScript that provides a wide range of functions for tasks like array manipulation, object cloning, and more. In this benchmark, lodash.assign() is used to create a copied object from the input data.

Special JS Feature/Syntax: Spread Operator

The spread operator (...) is a modern JavaScript feature introduced in ECMAScript 2015 (ES6). It allows you to expand an array or object into a new sequence of elements, creating a shallow copy of the original. In this benchmark, the spread operator is used to create a copied object from person and the new age object.

Alternatives

Other alternatives for object assignment might include:

• Using the Object.assign() method (built-in JavaScript function)
• Implementing a custom cloning function
• Using a different library or framework that provides an alternative implementation of object cloning

Keep in mind that these alternatives may have their own trade-offs and performance characteristics, depending on the specific use case and requirements.