Benchmark: js foreach vs map

Script Preparation code:

var arr = [];
for (var i = 0; i < 1000; i++) {
    arr[i] = i;
}

function someFn(i) {
    return i * 3 * 8;
}

Tests:

forEach
arr.forEach(function (item){ someFn(item); })
map
arr.map(item => someFn(item))

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
forEach
map

Fastest: N/A

Slowest: N/A

Latest run results:

No previous run results

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

LLMs can make mistakes. Check important info.

I'll explain what's being tested in the provided JSON benchmark.

**What is being tested?**

The provided JSON represents two individual test cases for JavaScript microbenchmarks on MeasureThat.net. The tests are designed to compare the performance of two approaches: `forEach` and `map`.

In the script preparation code, an array `arr` is created with 1000 elements, each initialized with a unique value. A function `someFn(i)` is also defined that takes an integer `i` as input and returns the result of multiplying `i` by 3 and then by 8.

The two test cases are:

1. **`forEach`**: The test uses the `forEach` method to iterate over the array, calling `someFn(item)` for each element.
2. **`map`**: The test uses the `map` method to create a new array with the results of applying `someFn(item)` to each element in the original array.

**Options compared**

The two approaches are compared in terms of performance, measured by the number of executions per second (ExecutionsPerSecond).

**Pros and Cons of each approach:**

1. **`forEach`**:
	* Pros:
		+ Easy to understand and implement.
		+ Works with any iterable type, not just arrays.
	* Cons:
		+ Can be slower than `map` for large datasets because it creates a new scope on each iteration.
2. **`map`**:
	* Pros:
		+ Generally faster than `forEach` for large datasets because it avoids creating a new scope on each iteration.
	* Cons:
		+ Requires an array (or other iterable) as input, which might not be the case in all scenarios.

**Other considerations:**

Both approaches have their own advantages and disadvantages. The choice between `forEach` and `map` ultimately depends on the specific use case and performance requirements.

For example:

* If you need to perform some side effect or modify an original array, `forEach` might be a better choice.
* If you need to create a new array with transformed values, `map` is often a better option.

**Library usage**

In this benchmark, the `Array.prototype.forEach()` and `Array.prototype.map()` methods are used. These are built-in JavaScript methods that operate on arrays. They don't require any external libraries or dependencies.

**Special JS features or syntax**

There are no special JavaScript features or syntax mentioned in this benchmark. The code is straightforward and doesn't utilize any advanced or experimental features.

**Alternatives**

If you need to compare the performance of other approaches, such as:

* `reduce()` (which is another built-in array method)
* Custom loops using `for` or `while`
* Other libraries like Lodash's `forEach` or `map` implementations
* Other languages or frameworks for similar operations

You can create additional benchmark test cases to compare these alternatives.

Related benchmarks:

js foreach vs map (version: 0)

Comparing performance of: forEach vs map

Created: 5 years ago by: Guest

Jump to the latest result

forEach

map

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

No previous run results

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