Benchmark: One iteration vs two comparable checks

Script Preparation code:

window.a = Array(1_000_000).fill(null).flatMap(() => [1, 2, 3, 4, 5])
window.b = [1, 2, 3, 4, 5]

Tests:

One iteration
for (let i = 0, l = a.length; i < l; i++) { if(b.some(y => (a[i] + y) === 'no')){ break; } if (!b.some(y => a[i] === y)) { break; } }
Two iterations
for (let i = 0, l = a.length; i < l; i++) { if(b.some(y => (a[i] + y) === 'no')){ break; } } for (let i = 0, l = a.length; i < l; i++) { if (!b.some(y => a[i] === y)) { break; } }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
One iteration
Two iterations

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/124.0.0.0 Safari/537.36

Browser/OS: Chrome 124 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
One iteration	0.4 Ops/sec
Two iterations	0.4 Ops/sec

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

LLMs can make mistakes. Check important info.

I'd be happy to explain the benchmark and its various aspects.

**Benchmark Overview**

The provided JSON represents a JavaScript microbenchmark on MeasureThat.net. The benchmark compares two approaches: one iteration vs two comparable checks in a `for` loop. The script preparation code initializes two arrays, `a` and `b`, with 1 million elements each.

**Options Compared**

There are two test cases:

1. **One Iteration**: This approach involves checking the condition only once for each iteration of the loop. It uses a single comparison in the condition.
2. **Two Iterations**: This approach involves checking both conditions (one after another) for each iteration of the loop, resulting in two comparisons per iteration.

**Pros and Cons**

- **One Iteration**:
  - Pros: Less overhead due to fewer function calls and less memory allocation compared to two iterations.
  - Cons: May be slower or more unpredictable due to the single condition check.
- **Two Iterations**:
  - Pros: Can provide a more accurate picture of performance since both conditions are checked for each iteration, which might better represent real-world usage.
  - Cons: Requires more function calls and memory allocation compared to one iteration.

**Library Used**

The `some()` method is used in the benchmark. The `Array.prototype.some()` method executes the provided callback function once for each element of an array, returning `true` as soon as it finds a condition that returns `true`.

**Special JavaScript Feature/Syntax**

There are no special JavaScript features or syntax explicitly mentioned in the benchmark.

**Other Considerations**

- **Cache Efficiency**: The results may vary depending on cache efficiency due to the repeated use of arrays and function calls.
- **Loop Unrolling**: Loop unrolling, a technique that can improve performance by reducing the overhead of loop iterations, might be beneficial here. However, it's not directly related to the compared approaches.

**Alternative Approaches**

Other alternatives could include:

1. **Different Data Structures**: Using different data structures, such as linked lists or trees, instead of arrays.
2. **Optimized Loop Conditions**: Optimizing the loop conditions by using techniques like dynamic branching (if-else) or more efficient algorithms for finding a condition that returns `true`.
3. **Native Language Support**: Compiling JavaScript to native machine code for better performance.

These alternatives would likely require significant changes to the benchmark script and might not be immediately relevant to this specific comparison of one iteration vs two comparable checks in a `for` loop.

Related benchmarks:

One iteration vs two comparable checks (version: 1)

Comparing performance of: One iteration vs Two iterations

Created: 2 years ago by: Registered User

Jump to the latest result

One iteration

Two iterations

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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