Let's break down the JavaScript microbenchmark on MeasureThat.net.

What is tested?

The benchmark tests two approaches:

1. Function equality: The first test case ("func") compares two functions defined using the let keyword with different return values: "HELLO" and "WORLD". The test checks whether these two functions are considered equal by JavaScript.
2. Object comparison: The second test case ("jsobj") compares two objects: one with a property named "hello" set to the string "world", and another with a property named "foo" set to the string "bar". The test checks whether these two objects are considered equal.

Options compared

The benchmark tests different approaches:

• Function equality: This approach compares the output of two functions, which can be affected by various factors such as function signature, argument types, and scope.
• Object comparison: This approach compares the contents of two objects, considering their property names and values.

Pros and cons of each approach:

1. Function equality:
   • Pros:
     • Can be useful for testing functions with specific signatures or behaviors.
     • May reveal issues related to function caching or memoization.
   • Cons:
     • Can be influenced by factors like argument types, scope, and function calls.
     • May not accurately represent real-world use cases where functions are used as values or passed around.
2. Object comparison:
   • Pros:
     • More relevant to real-world scenarios where objects are compared and used in arrays, maps, etc.
     • Can reveal issues related to object property access, mutation, and equality checks.
   • Cons:
     • May be slower due to the overhead of comparing properties.
     • Can lead to subtle differences between identical-looking objects (e.g., one being a primitive value while the other is an object reference).

Library/dependency

There is no explicit mention of any JavaScript libraries or dependencies in the provided code. However, MeasureThat.net likely uses some internal implementation to execute and compare functions and objects.

Special JS features/syntax

There are no special JavaScript features or syntax used in these test cases that would require additional explanation beyond their general functionality.

Other alternatives

If you wanted to rewrite this benchmark using alternative approaches, you might consider:

1. Using a different testing framework: Instead of MeasureThat.net's built-in implementation, you could use a separate testing framework like Jest or Mocha.
2. Testing with different browser versions: The benchmark currently only runs on Chromium 75. You could add more test cases to run the benchmarks on other browser versions or platforms (e.g., Firefox, Safari, Edge).
3. Incorporating additional scenarios: You might add more test cases to cover other aspects of function and object behavior, such as:
   • Testing for strict equality (===) versus loose equality (==).
   • Checking for specific error messages when comparing functions or objects.
   • Investigating the performance impact of using different comparison operators (e.g., ===, !==, ==, !=).