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

Latest run results:

Run details: (Test run date: 11 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

Autogenerated LLM Summary (model llama3.2:3b, generated 2 months 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.

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: 11 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 2 months ago):