Benchmark: Testing 4567_2 - MeasureThat.net

Script Preparation code:

var arr = [];
var count = 100000;
for(var i = 0; i<count; i++)
{
  arr.push(i);
}

Tests:

Cache length
var arrLen = arr.length; var sum = 0; for (var i = 0; i < arrLen; i++){ sum = arr[i]; }
Do not cache
var sum = 0; for (var i in arr){ sum = arr[i]; }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Cache length
Do not cache

Fastest: N/A

Slowest: N/A

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 and analyze the provided benchmark.

**Benchmark Overview**

The provided benchmark measures the performance difference between two approaches to saving the length of an array in a variable versus retrieving it within a loop. The test cases compare caching the array length or not caching it.

**Options Compared**

Two options are compared:

1. **Cache Length**: This approach saves the array length in a variable (`var arrLen = arr.length`) and uses it as the condition for the loop.
2. **Do Not Cache**: This approach does not save the array length in a variable and instead uses the `in` operator to check if each element is an index of the array.

**Pros and Cons**

* **Cache Length**:
	+ Pros: It avoids unnecessary iterations since the loop condition is directly based on the array length.
	+ Cons: The overhead of assigning a new value to `arrLen` might be higher than not using it at all. Additionally, this approach assumes that the array will have the same length for each iteration, which might not be the case in practice.
* **Do Not Cache**:
	+ Pros: This approach is simpler and does not require an extra assignment.
	+ Cons: It involves more iterations since the loop condition needs to check if each element is an index of the array using `in`. This can lead to slower performance.

**Library and Special Features**

There are no external libraries used in this benchmark. However, the use of the `in` operator (`for (var i in arr)`) is specific to JavaScript and allows iterating over the properties of an object (including arrays).

**Other Considerations**

When dealing with arrays in JavaScript, it's essential to consider the following:

* Array indices start from 0, not 1.
* Using `arr[i]` can be faster than using `arr[index]` since indexing is optimized for arrays.
* The `in` operator can lead to slower performance due to the overhead of iterating over the array's properties.

**Alternatives**

Other alternatives to compare in a benchmark could include:

* **Using `length` property directly**: Instead of assigning it to a variable, use `arr.length` directly in the loop condition.
* **Using `for...of` loop**: Consider using a `for...of` loop instead of a traditional `for` loop for iterating over arrays. The former is more concise and expressive.

These alternatives might provide different insights into the performance characteristics of each approach, depending on the specific use case and browser/interpreter used.

Latest run results:

Run details: (Test run date: 5 years ago)

User agent: Mozilla/5.0 (iPhone; CPU iPhone OS 13_2 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/13.0.3 Mobile/15E148 Safari/604.1

Browser/OS: Mobile Safari 13 on iOS 13.2

View result in a separate tab

Test name	Executions per second
Cache length	126.9 Ops/sec
Do not cache	120.0 Ops/sec

Related benchmarks:

Testing 4567_2 (version: 0)

save length of the array in the variable vs get it the loop

Comparing performance of: Cache length vs Do not cache

Created: 5 years ago by: Guest

Jump to the latest result

Cache length

Do not cache

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):