The benchmark defined in the provided JSON is focused on measuring the performance of JavaScript expressions that perform comparisons against null and undefined. It specifically evaluates four scenarios:

1. Checking Equality with null:

   • Benchmark Definition: callNull();
   • This function checks if a variable value is strictly equal to null (value === null), and also whether a variable valueNull is strictly equal to null.

2. Checking Equality with undefined:

   • Benchmark Definition: callUndefined();
   • This function checks if a variable value is strictly equal to undefined (value === undefined), and similarly checks if a variable valueUndefined is strictly equal to undefined.

3. Checking Non-Equality with null:

   • Benchmark Definition: callNotNull();
   • This function checks if a variable value is not equal to null (value !== null), and also whether valueNull is not equal to null.

4. Checking Non-Equality with undefined:

   • Benchmark Definition: callNotUndefined();
   • This function checks if a variable value is not equal to undefined (value !== undefined), and also checks if valueUndefined is not equal to undefined.

Performance Results

The benchmark results indicate the number of executions per second for each of these comparisons. The results reveal:

• The equality check against null (value === null) is the fastest with approximately 78.87 million executions per second.
• The equality check against undefined follows closely at about 77.03 million executions per second.
• The non-equality check against null has about 76.91 million executions per second.
• The non-equality check against undefined is the slowest at 73.94 million executions per second.

Pros and Cons of Approaches

• Equality Checks (===):

  • Pros: Direct and clear; using strict equality eliminates the risk of type coercion, leading to faster and more predictable results.
  • Cons: May be less performant than non-equality checks in certain contexts, though the difference here appears negligible.

• Non-Equality Checks (!==):

  • Pros: Useful in contexts where it is needed to confirm the absence of a value, such as checks before executing logic or functions.
  • Cons: Can be marginally slower, as indicated by the benchmark results, and might introduce confusion about the intended checks if not carefully handled.

Library and Code Explanation

The benchmark doesn't utilize any external libraries; it is entirely based on native JavaScript. The test revolves around primitive operations to assess performance in comparison to JavaScript's handling of null and undefined.

Both null and undefined represent "no value," but they are used in different contexts:

• null is typically an assignment value, meaning "no value intentionally."
• undefined represents a variable that has been declared but not assigned any value.

Other Alternatives

• Use of typeof operator: Instead of direct comparisons, one can use typeof variable === "undefined" for checks against undefined. This approach is usually more descriptive but introduces overhead and is thus expected to be slower in performance benchmarks.

• Logical Operators: In practice, sometimes the logical OR operator (||) can be employed for default value assignments or checks, e.g., let val = providedValue || default;, but such expressions vary from direct comparisons and are not directly covered in this benchmark.

Overall, this benchmark offers insights into fundamental comparative operations in JavaScript, highlighting performance aspects that might guide developers in making decisions based on execution speed versus clarity of intent.