Benchmark: Caching for loop conditions

Script Preparation code:

var arr = [...Array(1000).keys()];

Tests:

With cache
let sum = 0; for (let i = 0, arrLen=arr.length; i < arrLen; i++){ sum = arr[i]; }
Without cache
let sum = 0; for (let i = 0; i < arr.length; i++){ sum = arr[i]; }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
With cache
Without cache

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: one year ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/134.0.0.0 Safari/537.36

Browser/OS: Chrome 134 on Windows

View result in a separate tab

Test name	Executions per second
With cache	612271.4 Ops/sec
Without cache	468768.7 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down the provided benchmark and explain what's being tested, compared, and considered.

**Benchmark Definition**

The benchmark is defined by two test cases:

1. **With cache**: The loop iterates over an array of 1000 elements, storing its length in a variable `arrLen`. This allows the loop to skip unnecessary iterations, as it knows the exact number of elements.
2. **Without cache**: The loop iterates over the same array without caching the length.

**What's being tested**

The benchmark is testing the performance difference between these two approaches: using and not using an array length variable (`arrLen`) to determine the number of iterations in a loop.

**Options compared**

Two options are being compared:

1. **Cache**: Storing the array length in a variable `arrLen` before the loop.
2. **No cache**: Not storing the array length, relying on the built-in property `length` of the array to determine the number of elements.

**Pros and Cons**

**With Cache:**

Pros:

* Can avoid unnecessary iterations by using the cached value.
* May lead to better performance, especially for large arrays.

Cons:

* Requires additional memory to store the length variable.
* May increase code complexity if not used carefully.

**Without Cache:**

Pros:

* Does not require additional memory.
* Is a simpler and more straightforward approach.

Cons:

* May result in slower performance due to unnecessary iterations.

**Considerations**

Other factors that might affect the results include:

* Array size and density (e.g., sparse arrays vs. dense arrays).
* JavaScript engine optimizations and caching mechanisms.
* Platform, browser, and version differences.

**Library usage**

The test case uses no external libraries or dependencies.

**Special JS features or syntax**

There are no special JavaScript features or syntax used in this benchmark.

**Alternatives**

Other alternatives to testing performance of loops with array length variables might include:

* Testing the performance of different iteration methods, such as `for...of`, `forEach`, or `map`.
* Comparing the performance of other caching mechanisms, like memoization or caching in a separate data structure.
* Measuring the impact of loop unrolling, pipelining, or other optimization techniques.

Related benchmarks:

Caching for loop conditions (version: 0)

Comparing performance of with and without caching array length.

Comparing performance of: With cache vs Without cache

Created: 3 years ago by: Guest

Jump to the latest result

With cache

Without cache

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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