Benchmark: array.length - MeasureThat.net

Script Preparation code:

var arr = [];
var count = 1000;
for(var i = 0; i<count; i++)
{
  arr.push(i);
}

Tests:

cached
var arrLen = arr.length; var sum = 0; for (var i = 0; i < arrLen; i++){ sum = arr[i]; }
non-cached
var sum = 0; for (var 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
cached
non-cached

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; rv:109.0) Gecko/20100101 Firefox/114.0

Browser/OS: Firefox 114 on Windows

View result in a separate tab

Test name	Executions per second
cached	654906.0 Ops/sec
non-cached	605755.1 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's dive into the world of MeasureThat.net!

The provided JSON represents a JavaScript microbenchmark that tests the performance of two approaches: caching and non-caching of the `length` property of an array.

**Benchmark Definition**

The benchmark is defined by the `Script Preparation Code`, which initializes an empty array `arr` with 1000 elements using a loop. The `Html Preparation Code` is empty, indicating that no HTML-related code needs to be executed before running the benchmark.

**Options Compared**

Two options are compared:

1. **Cached**: This approach caches the result of `arr.length` in a variable `arrLen`. Then, in the main loop, it uses this cached value to iterate over the array elements.
2. **Non-Cached**: In this approach, the length of the array is not cached and is recalculated on each iteration.

**Pros and Cons**

* **Cached**:
	+ Pros: It reduces the number of times `arr.length` needs to be calculated, which can be expensive in terms of performance.
	+ Cons: If the length of the array changes during execution, the cached value will be out of sync, leading to incorrect results.
* **Non-Cached**:
	+ Pros: The result is always accurate and up-to-date, as it's recalculated on each iteration.
	+ Cons: It involves more expensive calculations for `arr.length` on each iteration.

Other considerations:

* Using a caching approach like `cached` can improve performance if the length of the array doesn't change frequently. However, if the length does change, the cached value will be incorrect.
* The choice between `cached` and `non-cached` ultimately depends on the specific use case and requirements.

**Library Used**

None.

**Special JS Features/Syntax**

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

Now, let's talk about alternative approaches:

1. **Use a library like Lodash**: If you need to perform array-related operations frequently, using a library like Lodash can provide a cached implementation of `array.length` and other methods.
2. **Use a Just-In-Time (JIT) compiler**: Some JavaScript engines, like V8 (used in Chrome), have JIT compilers that can optimize array access patterns like caching the length of an array.
3. **Write your own caching mechanism**: If you need fine-grained control over caching, you can write your own caching mechanism using a data structure like a hash table or a cache library.

Keep in mind that these alternatives may introduce additional complexity and overhead, so it's essential to evaluate their trade-offs before deciding which approach to use.

Related benchmarks:

array.length (version: 0)

Comparing performance of: cached vs non-cached

Created: one year ago by: Guest

Jump to the latest result

cached

non-cached

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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