Benchmark: void 0 and undefined in deep call stack

Tests:

compare window.undefined and void 0
function compare(n= 1e6){ for(let i = 0; i < n; i++){ undefined === void 0; } } function deep(num){ if (num === 0) { compare(); return; } else { deep(num-1); } } deep(100);
compare window.undefined and window.undefined
function compare(n= 1e6){ for(let i = 0; i < n; i++){ undefined === undefined; } } function deep(num){ if (num === 0) { compare(); return; } else { deep(num-1); } } deep(100);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
compare window.undefined and void 0
compare window.undefined and window.undefined

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 24 days ago):

LLMs can make mistakes. Check important info.

I'll break down the provided benchmark JSON and test cases to help explain what's being tested.

**Benchmark Overview**

The MeasureThat.net website allows users to create and run JavaScript microbenchmarks, which is essentially a way to measure the performance of small pieces of code. In this case, we have two benchmark definitions that test different scenarios:

1. `function compare(n= 1e6){...}`: This function loops `n` times (where `n` is 1 million) and checks if `undefined` is equal to `void 0`. The purpose of this benchmark is likely to assess the performance impact of using `undefined` vs. `void 0` equality checks.
2. `function deep(num){...}`: This function recursively calls itself with decreasing values of `num` until it reaches 0. It also calls the `compare` function within its own scope. The purpose of this benchmark is to test performance degradation due to scope chain when `undefined` is called from a deep stack.

**Options Compared**

In both benchmarks, we're comparing two different approaches:

1. `undefined === void 0`: This checks if `undefined` is equal to `void 0`, which is equivalent in JavaScript.
2. `undefined === undefined`: This checks if `undefined` is equal to itself.

The pros and cons of these approaches are as follows:

* Using `undefined === void 0`:
	+ Pros: This approach may be more efficient since `void 0` is a keyword that explicitly indicates an uninitialized or null value.
	+ Cons: It's less intuitive for some developers, especially those from older JavaScript versions.
* Using `undefined === undefined`:
	+ Pros: This approach is more explicit and easier to understand, as it clearly states the intention of comparing `undefined` with itself.
	+ Cons: It might be slightly slower since `undefined` needs to be dereferenced.

**Library and Special JS Feature**

In both benchmarks, we're using a custom-written script. There are no external libraries or special JavaScript features being tested here.

**Other Considerations**

When testing performance in JavaScript, it's essential to consider factors like:

* Loop unrolling: Some modern JavaScript engines optimize loop unrolling, which can impact benchmark results.
* Dead code elimination: Modern engines may eliminate dead code to reduce overhead. This might affect our benchmarks.
* Optimizations: Different browsers and JavaScript versions might implement optimizations that affect performance.

**Alternative Benchmarks**

If you wanted to create alternative benchmarks for these scenarios:

1. You could test the difference between `undefined` vs. a custom variable (e.g., `const foo = void 0;`) instead of using `void 0`.
2. To assess the impact of scope chain on performance, you might create a benchmark that recursively calls itself within a larger scope and measures the degradation.

Keep in mind that each benchmark is unique, and results may vary depending on the specific test case and JavaScript environment used.

Latest run results:

Run details: (Test run date: 9 months ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36

Browser/OS: Chrome 120 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
compare window.undefined and void 0	19.2 Ops/sec
compare window.undefined and window.undefined	9.5 Ops/sec

Related benchmarks:

void 0 and undefined in deep call stack (version: 0)

Check performance degradation due to scope chain when undefined is called from deep stack

Comparing performance of: compare window.undefined and void 0 vs compare window.undefined and window.undefined

Created: 9 months ago by: Guest

Jump to the latest result

compare window.undefined and void 0

compare window.undefined and window.undefined

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 24 days ago):