I'd be happy to help explain the benchmark.

What is being tested?

MeasureThat.net is testing three different approaches for merging two objects in JavaScript:

1. _.merge from Lodash library
2. Object.assign
3. Spread syntax ({ ...a, ...b })

These approaches are being compared to determine which one is the most efficient.

Options comparison

Here's a brief overview of each option and their pros and cons:

1. _

.merge from Lodash library

Pros:

• Well-maintained and widely used
• Supports complex merge logic (e.g., merging arrays, objects with nested properties)

Cons:

• Requires an external dependency (Lodash)
• May have slower startup times due to the dependency

The _.merge function takes two objects as input and returns a new merged object. It also supports other data types like arrays.

2. Object.assign

Pros:

• Built-in JavaScript method, no additional dependencies required
• Simple and straightforward implementation

Cons:

• Only works with objects, not with arrays or other data types
• Can lead to shallow merges if used incorrectly (i.e., merging an object into another object without creating a new target)

Object.assign is a built-in JavaScript function that takes multiple targets and an array of key-value pairs as arguments. When used with two objects, it returns a new merged object.

3. Spread syntax ({ ...a, ...b })

Pros:

• Native JavaScript syntax, no additional dependencies required
• Works with both objects and arrays

Cons:

• Introduced in ECMAScript 2018 (ES2018), might not be supported by older browsers or environments
• Can lead to slower performance due to the creation of a new object

The spread syntax allows you to create a new object by spreading an existing object's properties onto a target object. When used with two objects, it returns a new merged object.

Library and syntax features

Lodash is a popular utility library for JavaScript that provides various functions for tasks like string manipulation, array processing, and more. In this benchmark, _.merge is used to merge objects.

The spread syntax ({ ...a, ...b }) is a modern JavaScript feature introduced in ECMAScript 2018 (ES2018). It allows you to create a new object by spreading an existing object's properties onto a target object.

Other alternatives

If these three approaches are not sufficient for your needs, here are some additional options:

• Object.create: can be used to create a new object with the desired properties, but it requires more code and might lead to shallow merges if used incorrectly.
• Custom merge functions: you can write your own custom function to merge objects, but this approach requires more code and expertise.

Keep in mind that the best approach depends on your specific use case, performance requirements, and the environment where your code will run.