Benchmark: Caching length property vs getting it each time in the loop 10k

Script Preparation code:

var arr = [];
var count = 10000;
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 = 0; i < arr.length; i++){ 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

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

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Let's break down the benchmark and its test cases.

**Benchmark Overview**

The benchmark measures the performance of two approaches to calculate the sum of an array:

1. **Cache length property**: Store the length of the array in a variable outside the loop, then use this cached value as the upper bound for the loop.
2. **Get length each time in the loop**: Calculate the length of the array inside the loop.

**Options Compared**

The benchmark compares two options:

1. **Caching length property**: By storing the length of the array in a variable outside the loop, we avoid recalculating it on every iteration, which reduces the number of operations and potentially improves performance.
2. **Get length each time in the loop**: This approach recalculates the length of the array on every iteration, which can lead to slower performance due to the repeated calculations.

**Pros and Cons**

**Caching length property:**

Pros:

* Reduces the number of operations (calculating the length)
* Can improve performance by avoiding redundant calculations

Cons:

* Requires extra memory storage for the cached variable
* May not work well with arrays that are frequently resized or updated

**Get length each time in the loop:**

Pros:

* Easy to implement and understand
* Does not require extra memory storage

Cons:

* Repeatedly calculates the length of the array, which can lead to slower performance

**Other Considerations**

Both approaches assume that the length of the array does not change during the execution of the loop. If the array is frequently resized or updated, caching the length might not be effective.

**Library Usage (None)**

There are no libraries used in this benchmark.

**Special JS Features or Syntax (None)**

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

**Alternative Benchmarks**

Other alternatives to measure performance might include:

1. **Array iteration using `forEach()`**: Compare the performance of iterating over an array using `forEach()` with caching the length property versus not caching it.
2. **Array resizing and updating**: Measure the performance impact of frequently resizing or updating an array on different approaches to calculate the sum.
3. **Large datasets**: Benchmark the performance of these approaches on larger datasets (e.g., 100,000 elements) to observe any potential differences.

Keep in mind that the choice of benchmark and test cases ultimately depends on the specific use case and requirements.

Related benchmarks:

Caching length property vs getting it each time in the loop 10k (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>

Fastest: N/A

Slowest: N/A

No previous run results

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