I'll break down what's being tested, compared, and the pros/cons of different approaches.

What is being tested?

MeasureThat.net is testing the performance of _.isEqual from Lodash library. The test cases cover three levels of nested objects:

1. Level 1: Two identical objects with one level of nesting (foo1 and bar1)
2. Level 2: Two identical objects with two levels of nesting (foo2 and bar2)
3. Level 3: Two identical objects with three levels of nesting (foo3 and bar3)

The test also includes a simple comparison using the === operator on stringified versions of the objects.

What options are compared?

In this benchmark, only two options are being compared:

1. Lodash's _isEqual function
2. A simple === operator comparison

Pros and Cons:

Lodash's _isEqual function:

Pros:

• Handles nested objects recursively
• Can be used to compare complex data structures
• Part of a well-maintained library with a wide range of features

Cons:

• May have performance overhead due to the recursive nature of the comparison
• Requires an external dependency (Lodash)

Simple === operator comparison:

Pros:

• Fast and lightweight
• Does not require any external dependencies

Cons:

• Only works for primitive types or stringified versions of objects
• Does not handle nested objects recursively
• May lead to false positives if the objects being compared are not exactly equal

Other considerations:

The benchmark also includes a comparison using JSON.stringify, which can be useful in certain situations, such as when comparing JSON data. However, this approach may not work well for all types of data and may lead to performance issues due to the overhead of stringifying objects.

Lodash library and its purpose:

Lodash is a popular JavaScript utility library that provides a wide range of functions for tasks such as array manipulation, object transformation, and functional programming. The _isEqual function is specifically designed to compare two values for equality, handling nested objects and arrays recursively.

If you're not familiar with Lodash, it's worth exploring its documentation and examples to learn more about the library and its features.

Special JS feature or syntax:

There are no special JavaScript features or syntax used in this benchmark. The code is straightforward and uses only standard JavaScript constructs.

Other alternatives to MeasureThat.net include:

• Benchmarking libraries like Benchmark.js, which provide a simple way to write benchmarks using Node.js.
• Online testing platforms like jsPerf, which allow you to test your code's performance in a head-to-head format against others.