Benchmark: map vs. for vs. for in vs. forEach

Script Preparation code:

var a = ["foo", "bar", "baz", "boom"]

Tests:

map
var b = a.map(function(c) { return c; });
for in
var b = []; for (var i in a) { b.push(a[i]); }
for
var b = []; for (var i = 0; i < a.length; i++) { b.push(a[i]); }
forEach
var b = []; a.forEach(function(c) { b.push(c); });

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
map
for in
for
forEach

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 24 days ago)

User agent: Mozilla/5.0 (X11; Linux x86_64; rv:133.0) Gecko/20100101 Firefox/133.0

Browser/OS: Firefox 133 on Linux

View result in a separate tab

Test name	Executions per second
map	38556696.0 Ops/sec
for in	4239862.5 Ops/sec
for	78846720.0 Ops/sec
forEach	41818144.0 Ops/sec

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

LLMs can make mistakes. Check important info.

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

**Benchmark Definition:**
The benchmark definition JSON object provides information about the benchmark, but it doesn't contain much detail. However, based on the script preparation code and individual test cases, we can infer that the benchmark compares different methods for iterating over an array:

* `map`: A method that creates a new array with the results of applying a provided function to each element in the original array.
* `for` (or "for loop"): A traditional loop that iterates over the indices and values of an array using a `for` loop statement.
* `for in`: A loop that iterates over the properties (i.e., elements) of an object. In this case, it's being used to iterate over the array by accessing its elements as if they were properties of an object.
* `forEach`: A method that executes a provided function once for each element in an array.

**Options Compared:**
The benchmark compares these four options:

1. **`map`**: Creates a new array with transformed elements
2. **`for`**: Iterates over indices and values using a traditional loop
3. **`for in`**: Iterates over properties (elements) of an object, used to iterate over the array
4. **`forEach`**: Executes a function once for each element

**Pros and Cons:**

* **`map`**: Pros:
	+ Creates a new array with transformed elements, which can be useful if you need to process data in a specific way.
	+ Can be faster than traditional loops for large arrays.
Cons:
	+ Creates an additional array, which can consume memory.
	+ May not be suitable for cases where you only need to perform a simple operation on each element.
* **`for`**: Pros:
	+ Traditional loop that's easy to understand and implement.
	+ Doesn't create any new data structures.
Cons:
	+ Can be slower than array methods like `map` or `forEach` for large arrays due to the overhead of indexing and looping.
* **`for in`**: This option is not typically used for iterating over arrays, but it's being used here as a curiosity test. Pros: None notable. Cons:
	+ Inefficient and unnecessary for this use case.
	+ Can lead to unexpected behavior if you're not aware of its quirks.
* **`forEach`**: Pros:
	+ Executes a function once for each element in the array, making it suitable for operations that only need to perform a simple action on each element.
Cons:
	+ May be slower than traditional loops or `map` for large arrays due to the overhead of function invocation.

**Library Usage:**
None of the individual test cases use any external libraries. The `map`, `forEach`, and `for` methods are all part of the JavaScript language itself.

**Special JS Features/Syntax:**
There's no special JavaScript feature or syntax being tested in this benchmark. It's a straightforward comparison of different iteration methods.

**Alternatives:**
If you're looking for alternative benchmarks, you might consider:

* Comparing other array methods like `filter`, `reduce`, or `slice`.
* Testing the performance of different data structures, such as arrays vs. linked lists.
* Evaluating the performance of JavaScript engines and browsers under various workloads.

Keep in mind that the choice of benchmark depends on your specific use case and goals.

Related benchmarks:

map vs. for vs. for in vs. forEach (version: 2)

Comparing performance of: map vs for in vs for vs forEach

Created: 8 years ago by: Registered User

Jump to the latest result

map

for in

for

forEach

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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