Benchmark: .map() vs for-of + push

Script Preparation code:

var list = Array.from(new Array(10000)).map((_, i) => i)
var result = []

Tests:

for-of + push
for (const value of list) { result.push(value * 2); }
map
result = list.map(v => v * 2);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
for-of + push
map

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:139.0) Gecko/20100101 Firefox/139.0

Browser/OS: Firefox 139 on Windows

View result in a separate tab

map

28K/s

for-of + push

4K/s

View exact numbers

Test name	Executions per second
✓ map	27,602 Ops/sec
for-of + push	4,038 Ops/sec

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

LLMs can make mistakes. Check important info.

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

**Benchmark Definition**

The benchmark definition specifies two test cases:

1. `.map() vs for-of + push`
2. `for (const value of list) { ... }` and `result = list.map(v => v * 2);`

These test cases are comparing the performance of using the `Array.prototype.map()` method versus creating a for-of loop with the `push()` method to iterate over an array.

**Options compared**

The two options being compared are:

* `.map()`: A built-in JavaScript method that creates a new array by applying a provided function to each element of the original array.
* For-of loop with `push()`: A manual iteration approach using a for-of loop and the `push()` method to add elements to an array.

**Pros and Cons**

**.map():**

Pros:

* Convenient and concise syntax
* No need to worry about indexing or iterating manually
* Can be faster than a manual iteration approach, as it's implemented in native code

Cons:

* Creates a new array, which can consume memory
* May not perform well for very large arrays due to the overhead of creating an intermediate array

For-of loop with `push()`:

Pros:

* No memory allocation or copying, making it suitable for large arrays
* Allows manual control over iteration and indexing

Cons:

* Can be more verbose and harder to read than `.map()`
* May require additional calculations or indexing logic

**Other considerations**

When choosing between these two approaches, consider the following factors:

* **Memory constraints**: If memory is a concern, the for-of loop with `push()` might be a better choice.
* **Readability and maintainability**: If code readability and maintainability are more important than performance, `.map()` might be a better option.
* **Array size**: For very large arrays, the performance difference between these two approaches might be negligible.

**Library**

There is no explicit library mentioned in the benchmark definition. However, it's likely that the `Array.prototype.map()` method and the for-of loop with `push()` are built-in JavaScript features or part of a standard library.

**Special JS feature/syntax**

There is no special JS feature or syntax explicitly mentioned in the benchmark definition. The test cases only rely on basic JavaScript concepts like arrays, loops, and functions.

Now, let's look at some alternative approaches that could be used to compare performance:

1. **Looping through an array using `forEach()`**: This approach would create a new array by calling the callback function for each element in the original array.
2. **Using `reduce()`**: This approach would apply a reduction function to the array, accumulating a result for each element.
3. **Manual iteration with indexing**: This approach would use manual indexing to access and manipulate elements of the array.

These alternatives could be used to create additional test cases that compare performance in different scenarios.

.map() vs for-of + push (version: 0)

Comparing performance of: `for-of + push vs map`

Created: 2 years ago by: Guest

Go to the latest result

for-of + push

map

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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

.map() vs for-of + push (version: 0)

Comparing performance of: for-of + push vs map

Created: 2 years ago by: Guest

Go to the latest result

for-of + push

map

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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

Related benchmarks

Comparing performance of: `for-of + push vs map`