Let's break down the provided benchmark and explain what's being tested, compared, and their pros/cons.

Benchmark Overview

The benchmark measures the performance of two JavaScript libraries: jsondiffpatch and FAST JSON-patch (also known as jsonpatch). The test case involves comparing two objects (obj1 and obj2) for differences. Specifically, it checks how quickly each library can compute these differences.

Options Compared

There are three options being compared:

1. JSON-Diff Patch (jsondiffpatch): This library provides a method called diff() that computes the differences between two objects.
2. FAST JSON-Patch: This library provides methods like compare(), which also computes object differences, and applyPatch() to apply those differences.

Pros/Cons of Each Approach

1. JSON-Diff Patch (jsondiffpatch):
   • Pros: Simple to use, straightforward API.
   • Cons: Might be slower due to the way it calculates differences.
2. FAST JSON-Patch:
   • Pros: Optimized for performance, efficient algorithm.
   • Cons: Can be more complex to use compared to jsondiffpatch.

Library Descriptions

1. JSON-Diff Patch (jsondiffpatch): A JavaScript library that provides a simple and efficient way to compute differences between two objects. It's designed for patching JSON data.
2. FAST JSON-Patch: A lightweight, optimized library developed by Mozilla. Its primary goal is to efficiently handle JSON patches in web applications.

Special JS Features/Syntax

None mentioned explicitly in the provided benchmark. However, it's worth noting that jsonpatch and jsondiffpatch both rely on the concept of "patches" – a set of operations (additions, deletions, or modifications) to apply to an original object.

Alternative Alternatives

Other alternatives for JSON diffing include:

1. JSON Patch: A simple, human-readable format for describing changes to a JSON document.
2. Lodash's diff() function: Another JavaScript library that computes differences between two objects.
3. DeepDiff: A more comprehensive library for computing object differences.

In summary, the benchmark compares the performance of jsondiffpatch and FAST JSON-patch libraries in computing object differences. The choice between these libraries depends on your specific use case, with jsondiffpatch offering simplicity at the cost of potentially slower performance and FAST JSON-patch prioritizing efficiency but with a more complex API.