Benchmark: void 0 and undefined in deep call stack - 2

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(10);
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(10);

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: 2 years 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	19.0 Ops/sec
compare window.undefined and window.undefined	9.5 Ops/sec

Autogenerated LLM Summary (model llama3.2:3b, generated one year ago):

LLMs can make mistakes. Check important info.

**What is being tested?**

MeasureThat.net is testing the performance of JavaScript in two different scenarios:

1. **`undefined === void 0`**: This test case checks how the JavaScript engine performs when comparing `undefined` with `void 0`. The idea is to see if the engine uses an optimized path for this comparison, which might involve checking the type of the variables or using a specialized optimization.
2. **`window.undefined and window.undefined`**: In this test case, the engine is expected to compare two identical values: `window.undefined` (note the space between `w` and `i`) with itself. This test aims to measure how the engine handles self-comparisons, which can be a micro-optimization.

**Options compared**

The options being compared in these tests are:

* Using `undefined === void 0` vs. using `window.undefined`
* Self-comparison (`window.undefined and window.undefined`) vs. comparing with a different value

**Pros and cons of each approach:**

1. **`undefined === void 0`**:
	* Pros: This comparison is more likely to be optimized by the engine, as it's a common use case.
	* Cons: It may not accurately measure performance in all scenarios where `void 0` is used differently (e.g., with `var`, `let`, or `const` declarations).
2. **Self-comparison (`window.undefined and window.undefined`)**:
	* Pros: This test can help identify performance issues specific to self-comparisons, which might not be caught by other tests.
	* Cons: The engine may use an optimized path for this comparison as well, making it harder to distinguish between the two tests.

**Other considerations**

When interpreting the results:

* **Timing variability**: Execution times can vary due to factors like CPU frequency, memory pressure, or browser-specific optimizations. Take these variations into account when drawing conclusions about performance differences.
* **JavaScript engine-specific behavior**: Different JavaScript engines (e.g., V8 for Chrome) may exhibit unique characteristics when executing these tests.

**Library and special JS feature**

No libraries are explicitly mentioned in the test cases provided. However, `void 0` is used instead of just `undefined`, which is a common convention to ensure consistency across environments.

The use of `$` (dollar sign) in the benchmark definition is not present in these examples.

Related benchmarks:

void 0 and undefined in deep call stack - 2 (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: 2 years 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>

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated one year ago):