Benchmark: Testing 4567 - MeasureThat.net

Script Preparation code:

var arr = [];
var count = 1000;
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

Latest run results:

No previous run results

This benchmark does not have any results yet. Be the first one to run it!

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.

**Benchmark Definition**

The website provides a JSON object that defines two test cases:

1. **Saving array length in a variable**: This script preparation code creates an empty array `arr` and then uses a loop to push 1000 elements onto it, overwriting any existing content.
```javascript
var arr = [];
var count = 1000;
for (var i = 0; i < count; i++) {
  arr.push(i);
}
```
The HTML preparation code is empty (`null`), which means no additional HTML is generated for this test case.

2. **Getting array length using `in` operator**: This script preparation code creates an empty array `arr` and then uses a loop to access each element of the array, using the `in` operator to iterate over the array's indices.
```javascript
var sum = 0;
for (var i in arr) {
  sum = arr[i];
}
```
**Options Compared**

In both test cases, we have two approaches:

1. **Saving array length in a variable**: This method stores the array length in a separate variable (`arrLen`) and then uses that value to determine the loop's termination condition.
2. **Getting array length using `in` operator**: This method uses the `in` operator to iterate over the array's indices, which returns an iterable object (an array-like object).

**Pros and Cons**

1. **Saving array length in a variable**:
	* Pros: Can be more efficient because it avoids accessing the array itself during iteration.
	* Cons: Requires additional memory allocation for the `arrLen` variable.
2. **Getting array length using `in` operator**:
	* Pros: Does not require additional memory allocation, as the `in` operator works with references to elements in the array.
	* Cons: May be slower due to the overhead of iterating over the array's indices.

**Library and Special JS Feature**

There is no library used in this benchmark. However, it does use a special JavaScript feature: **for...of loops are not yet supported for arrays**, which means that using `in` operator is a common work-around when working with arrays. The `for...in` loop syntax is available, but it has some quirks and limitations.

**Other Alternatives**

There are other ways to optimize array iteration:

1. **Using `Array.prototype.length`**: Instead of saving the array length in a variable, you can access it directly using the `Array.prototype.length` property.
```javascript
var arr = [];
for (var i = 0; i < arr.length; i++) {
  // ...
}
```
2. **Using `slice()` method**: You can use the `slice()` method to create a new array with the desired number of elements, which can be more efficient than iterating over the entire array.
```javascript
var arr = [];
for (var i = 0; i < 1000; i++) {
  arr.push(i);
}
// Later...
var first1000 = arr.slice(0, 1000);
```
However, these alternatives may not be relevant to this specific benchmark, as they introduce additional complexity and may not provide a significant performance benefit.

Related benchmarks:

Testing 4567 (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: 6 years ago by: Guest

Jump to the latest result

Cache length

Do not cache

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

No previous run results

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