Benchmark: setting array length + assignation vs assignation vs push

Tests:

Set length and assignation
var size = 100000; var arr2 = []; arr2.length = size; for (var i = 0; i < size; i++){ arr2[i] = i; }
Push
var size = 100000; var arr3 = []; for (var i = 0; i < size; i++){ arr3.push(i); }
Assignation
var size = 100000; var arr2 = []; for (var i = 0; i < size; i++){ arr2[i] = i; }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Set length and assignation
Push
Assignation

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 6 months ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/140.0.0.0 Safari/537.36

Browser/OS: Chrome 140 on Windows

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Test name	Executions per second
Set length and assignation	6580.6 Ops/sec
Push	2159.3 Ops/sec
Assignation	1977.3 Ops/sec

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

LLMs can make mistakes. Check important info.

Measuring the performance of different approaches to setting array length and assigning values in JavaScript is an interesting benchmark.

**Benchmark Definition**

The provided JSON defines three individual test cases:

1. **"Set length and assignation"**: This test case assigns a value to each index of the array using `arr2[i] = i;`. The array length is set using `arr2.length = size;`.
2. **"Push"**: This test case uses the `push()` method to add elements to the end of the array, without setting the initial length.
3. **"Assignation"**: This test case assigns a value to each index of the array without setting the initial length.

**Options Compared**

The benchmark compares three different approaches:

1. **Assigning values using indexing (`arr2[i] = i;`) and setting the length explicitly (`arr2.length = size;`)**: This approach is straightforward and easy to understand.
2. **Using `push()`**: The `push()` method adds elements to the end of the array without modifying the existing elements. This can be more efficient than assigning values using indexing for large arrays.
3. **Assigning values directly without setting the length (`arr[i] = i;`)**: This approach avoids setting the initial length, but it may lead to slower performance due to the overhead of dynamically resizing the array.

**Pros and Cons**

Here are some pros and cons of each approach:

1. **Assigning values using indexing and setting the length explicitly**:
	* Pros: Easy to understand, simple implementation.
	* Cons: May be slower for large arrays due to the overhead of setting the initial length.
2. **Using `push()`**:
	* Pros: Efficient for large arrays, avoids modifying existing elements.
	* Cons: May lead to slower performance if the array is dynamically resized frequently.
3. **Assigning values directly without setting the length**:
	* Pros: Avoids setting the initial length, potentially faster for small arrays.
	* Cons: May lead to slower performance due to dynamic resizing.

**Libraries and Special Features**

None of the test cases use any specific JavaScript library or feature that is not part of the standard language.

**Other Alternatives**

If you're interested in exploring alternative approaches, here are a few:

1. **Using `Array.prototype.set()`**: This method allows setting the length of an array and assigning values simultaneously.
2. **Using `Array.prototype.fill()`**: This method fills all elements of an array with a given value, which can be more efficient than using indexing.

Keep in mind that these alternatives may have different performance characteristics or use cases compared to the approaches tested in this benchmark.

Overall, the benchmark provides a useful comparison of three common approaches to setting array length and assigning values in JavaScript. The results highlight the importance of considering the specific requirements and constraints of your application when choosing an approach.

Related benchmarks:

setting array length + assignation vs assignation vs push (version: 0)

Comparing performance of: Set length and assignation vs Push vs Assignation

Created: 3 years ago by: Guest

Jump to the latest result

Set length and assignation

Push

Assignation

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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