Benchmark: map vs forEach Chris v2b

Script Preparation code:

var largeArray = Array(1000000).fill('x');

Tests:

map
largeArray.map( (value) => { value+'y' });
forEach
largeArray.forEach((value) => { value +'y';});

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
map
forEach

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 9 months ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:141.0) Gecko/20100101 Firefox/141.0

Browser/OS: Firefox 141 on Windows

View result in a separate tab

Test name	Executions per second
map	203.5 Ops/sec
forEach	600.7 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's dive into the world of JavaScript microbenchmarks and explore what's being tested on MeasureThat.net.

**What is being tested?**

The provided JSON represents two individual test cases: `map` and `forEach`. These are two popular methods in JavaScript for iterating over arrays. The goal is to compare their performance when applied to a large array.

**Options compared**

In this benchmark, the following options are being compared:

1. `Array.prototype.map()`: This method creates a new array with the results of applying a provided function to each element in the original array.
2. `Array.prototype.forEach()`: This method executes a callback function for each element in the array, but unlike `map`, it does not return any value.

**Pros and Cons of different approaches**

*   **`map()`**: Pros:
    *   Returns a new array with transformed elements
    *   Can be used as a one-time operation
    *   Allows for easier error handling and testing
*   Cons:
    *   Creates an additional data structure (a new array), which can consume memory
    *   May have slower performance due to the overhead of creating a new array
*   **`forEach()`**: Pros:
    *   Does not create any additional data structures, making it more memory-efficient
    *   Can be used for side effects or mutations that do not return values
    *   More concise and easier to read for simple operations
*   Cons:
    *   Does not return any value, making it harder to use in certain situations (e.g., when you need the transformed elements)
    *   May have slower performance due to the overhead of executing a callback function

**Library and purpose**

In this benchmark, no libraries are explicitly mentioned. However, `Array.prototype` is being used, which is a built-in JavaScript object that provides methods for array operations.

**Special JS feature or syntax**

There doesn't seem to be any special JavaScript features or syntax being tested in this benchmark.

**Other alternatives**

If you're looking for alternative approaches, here are a few options:

1.  **`reduce()`**: Instead of using `map()` or `forEach()`, you can use the `reduce()` method to transform an array.
2.  **Closures**: You can create a closure by defining a function that takes an array as an argument and returns a new array with transformed elements.
3.  **Loops**: If you're comfortable with low-level memory management, you can write a loop to iterate over the array and perform transformations.

These alternatives may have different performance characteristics or use more resources compared to `map()` and `forEach()`. However, they provide more control and flexibility in certain situations.

**Benchmark preparation code**

The benchmark preparation code is:
```javascript
var largeArray = Array(1000000).fill('x');
```
This creates a new array with 1 million elements, all initialized to the string `'x'`.

**Individual test cases**

There are two individual test cases:

*   `map`: This test case applies the `(value) => { value+'y' }` function to each element in the `largeArray`, which returns a new array with transformed elements.
*   `forEach`: This test case executes the `(value) => { value +'y';}` callback function for each element in the `largeArray`, but does not return any value.

These test cases are executed multiple times and provide performance data, allowing users to compare the execution speed of `map()` and `forEach()`.

Related benchmarks:

map vs forEach Chris v2b (version: 0)

performance test map vs forEach

Comparing performance of: map vs forEach

Created: 5 years ago by: Guest

Jump to the latest result

map

forEach

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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