Benchmark: push vs length as filter

Script Preparation code:

var length = 2000

Tests:

push
var a = []; for (let i = 0; i < length; i += 1) { if (i % 2) { a.push(i); } }
length
var a = Array(length); var offset = 0; for (let i = 0; i < length; i += 1) { if (i % 2) { a[offset++] = i; } } a.length = offset;

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
push
length

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: one year ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:109.0) Gecko/20100101 Firefox/116.0

Browser/OS: Firefox 116 on Mac OS X 10.15

View result in a separate tab

Test name	Executions per second
push	129817.7 Ops/sec
length	106599.6 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 JavaScript microbenchmarks on MeasureThat.net.

**Benchmark Definition**

The provided JSON defines two benchmark tests: `push` and `length`. These tests measure the performance of two different approaches for filtering elements in an array.

**Options Compared**

There are two options being compared:

1. **Using `Array.prototype.push()`**: This approach involves iterating over a range of numbers, pushing them onto the end of an empty array using `Array.prototype.push()`, and then accessing the resulting length of the array to determine how many elements were pushed.
2. **Using indexing (`offset`) to access elements directly**: Instead of using `push()`, this approach uses an `offset` variable to keep track of the current position in the array, pushing numbers onto the array at that offset.

**Pros and Cons**

### Using `Array.prototype.push()`:

Pros:

* Easier to implement and understand for developers who are familiar with JavaScript arrays.
* Can be a good choice when the performance difference is not critical.

Cons:

* Pushing elements onto the end of an array can lead to slow performance due to the overhead of resizing the internal buffer (called the "heap").
* Accessing the length property after pushing can add additional overhead.

### Using indexing (`offset`) to access elements directly:

Pros:

* Can avoid some of the overhead associated with `push()` by accessing elements directly.
* May provide better cache locality, which can lead to improved performance.

Cons:

* Requires manual management of an `offset` variable, which can be error-prone and harder to understand for developers who are not familiar with it.
* If the `offset` is incorrect or out of bounds, it can lead to crashes or unexpected behavior.

**Library and Special Features**

There are no libraries mentioned in the provided benchmark definition. However, if a library were used, some possible candidates could be:

* Lodash's `chunk()` function, which can create an array of elements with a specified length.
* Ramda's `filter()` function, which can filter elements from an array.

**Special JavaScript Features or Syntax**

There are no special JavaScript features or syntax mentioned in the provided benchmark definition. However, if a test case used some special feature, it could be related to:

* Array.prototype methods (e.g., `forEach()`, `map()`, `filter()`).
* Generators or iterators.
* ES6+ features like `for...of` loops or async/await.

**Other Alternatives**

If you wanted to test alternative approaches for filtering elements in an array, some possible options could be:

* Using `slice()` to create a new array with the filtered elements.
* Using a custom implementation of `filter()` using recursion or iteration.
* Using a third-party library like Underscore.js or Ramda.

Keep in mind that these alternatives may have different trade-offs and performance characteristics compared to the original benchmark tests.

Related benchmarks:

push vs length as filter (version: 0)

Comparing performance of: push vs length

Created: one year ago by: Registered User

Jump to the latest result

push

length

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):