Benchmark: Array loop vs foreach vs map with Random

Script Preparation code:

   var arr = [];
    for (var i = 0; i < 1000; i++) {
      arr[i] = i;
    }
  
    function someFn(i) {
      return i * 3 * Math.random();
    }

Tests:

foreach
arr.forEach(function (item){ someFn(item); })
for
for (var i = 0, len = arr.length; i < len; i++) { someFn(arr[i]); }
map
arr.map(item => someFn(item))

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
foreach
for
map

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 24 days ago):

LLMs can make mistakes. Check important info.

Let's dive into the world of JavaScript microbenchmarks!

The provided JSON represents a benchmark test created on MeasureThat.net, which compares the performance of three different approaches to iterate over an array: `forEach`, `for`, and `map`.

**Benchmark Test**

The test is designed to measure the execution speed of the `someFn` function (a simple multiplication and randomization function) applied to each element in a randomly generated array of 1000 elements.

**Options Compared**

1. **`forEach`**: The `forEach` method applies a provided callback function to each element in an array, without explicitly iterating over the array's indices.
2. **`for`**: A traditional, explicit loop using a `for` statement to iterate over the array's indices.
3. **`map`**: The `map` method creates a new array with the results of applying a provided callback function to each element in an array.

**Pros and Cons**

*   **`forEach`**:
    *   Pros: concise, easy to read, and relatively efficient since it doesn't require explicit indexing.
    *   Cons: may be slower due to the overhead of creating a callback function for each iteration.
*   **`for`**:
    *   Pros: well-known, widely supported, and can be optimized for performance by using a `for` loop with a cached array length.
    *   Cons: more verbose than `forEach`, requires manual indexing, which can lead to errors if not done correctly.
*   **`map`**:
    *   Pros: concise, easy to read, and efficient since it avoids the need for explicit indexing by creating a new array with the results.
    *   Cons: may be slower due to the overhead of creating a new array.

In terms of performance, `for` is generally the fastest option because it allows for optimized caching of the array's length and eliminates the overhead of callback function creation. However, `map` is often used in modern JavaScript development due to its concise syntax and simplicity.

**Library/Extension: None**

This benchmark does not utilize any external libraries or extensions other than built-in JavaScript features.

**Special JS Features/Syntax:**

The test uses a simple multiplication and randomization function (`someFn`) that leverages the `Math.random` function, which is a standard part of the JavaScript language.

Latest run results:

Run details: (Test run date: 2 years ago)

User agent: Mozilla/5.0 (Linux; Android 10; Redmi Note 7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/99.0.4844.58 Mobile Safari/537.36

Browser/OS: Chrome Mobile 99 on Android

View result in a separate tab

Test name	Executions per second
foreach	1325.8 Ops/sec
for	1053.6 Ops/sec
map	1249.4 Ops/sec

Related benchmarks:

Array loop vs foreach vs map with Random (version: 0)

Comparing performance of: foreach vs for vs map

Created: 3 years ago by: Guest

Jump to the latest result

foreach

for

map

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 24 days ago):