Benchmark: filter vs spread filter

Tests:

filter
const arr = Array.from(Array(1000)).map((_, i) => i); const newArr = arr.filter(i => i % 2 === 0);
spread filter
const arr = Array.from(Array(1000)).map((_, i) => i); const newArr = [...arr.filter(i => i % 2 === 0)];

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
filter
spread filter

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 3 years ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/94.0.4606.54 Safari/537.36

Browser/OS: Chrome 94 on Windows

View result in a separate tab

Test name	Executions per second
filter	179887.7 Ops/sec
spread filter	164435.0 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down the provided benchmark and explain what's being tested.

The provided JSON represents a JavaScript microbenchmark, which is a small piece of code designed to measure the performance of specific parts of the JavaScript engine. The benchmark consists of two test cases:

1. `filter`
2. `spread filter`

**What is being tested?**

In both test cases, an array of 1000 elements is created using `Array.from(Array(1000)).map((_, i) => i)`. This creates an array where each element is a number from 0 to 999.

The difference between the two test cases lies in how the even numbers are filtered out:

**Test Case 1: `filter`**

```javascript
const newArr = arr.filter(i => i % 2 === 0);
```

In this case, the `Array.prototype.filter()` method is used to create a new array that only includes elements from the original array where the expression `i % 2 === 0` evaluates to true.

**Test Case 2: `spread filter`**

```javascript
const newArr = [...arr.filter(i => i % 2 === 0)];
```

In this case, the spread operator (`...`) is used in conjunction with the `Array.prototype.filter()` method. The filtered array is then spread into a new array using the spread operator.

**Options compared**

The two test cases compare the performance of these two different approaches:

* `filter` (without the spread operator)
* `spread filter` (with the spread operator)

**Pros and Cons**

**Test Case 1: `filter`**

Pros:

* Easier to read and understand
* Less memory allocation required, as only one array is created

Cons:

* May be slower due to the additional memory allocation required by the spread operator in the second test case

**Test Case 2: `spread filter`**

Pros:

* Faster performance, as less memory allocation is required
* Still readable and understandable, although slightly more complex

Cons:

* More memory allocated, which may impact performance for very large arrays

**Library usage**

None of the provided code snippets use any external libraries. The `Array.from()` method and the spread operator are built-in JavaScript features.

**Special JS feature or syntax**

The use of the spread operator (`...`) in Test Case 2 is a relatively modern feature introduced in ECMAScript 2015 (ES6). It allows for efficient array creation without using the `Array.prototype.slice()` method.

**Other alternatives**

If the benchmark were to compare other approaches, some possible alternatives could include:

* Using `slice()` instead of spread operator
* Using a custom filtering function
* Using a library like Lodash's `filter()` function

However, in this specific case, the test cases only compare two simple and straightforward approaches: using the `Array.prototype.filter()` method with or without the spread operator.

Related benchmarks:

filter vs spread filter (version: 0)

Comparing performance of: filter vs spread filter

Created: 3 years ago by: Guest

Jump to the latest result

filter

spread filter

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):