Benchmark: map vs foreach for the millionth time

HTML Preparation code:

<script>
  const arr = [x => x + 1, y => y + 2, z => z + 3]
</script>

Tests:

map
arr.map(fn => fn(100))
for
arr.forEach(fn => fn(100))

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
map
for

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):

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Let's break down what's being tested in this benchmark.

**Benchmark Definition:**
The benchmark is comparing the performance of two approaches: `map` and `forEach`. Both methods are used to iterate over an array, but they differ in how they handle function invocation.

**Options compared:**

1. **Map**: The `map()` method applies a given function to each element of an array and returns a new array with the results.
2. **ForEach**: The `forEach()` method executes a provided function once for each element in an array.

**Pros and Cons:**

* **Map**: Pros:
	+ Returns a new array with transformed elements, which can be useful if you need to process the result of the transformation.
	+ Can be more memory-efficient than using `forEach` if you don't need to mutate the original array.
*   Cons:
	+ Requires creating a new array, which can lead to increased memory usage and slower performance for large datasets.
*   **ForEach**: Pros:
	+ Does not create a new array, making it more memory-efficient.
	+ Can be faster since it doesn't require an extra array creation step.
*   Cons:
	+ The original array is modified in place (if you pass a function that modifies the element), which can lead to unexpected behavior if you're not expecting it.

**Library usage:**
There is no library explicitly used in this benchmark. However, it's worth noting that `forEach` is a built-in method of the Array prototype, so no additional libraries are required.

**Special JS feature or syntax:**
The `map()` and `forEach()` methods use a shorthand syntax for callback functions, which is allowed by ECMAScript 2015 (ES6) and later standards. This allows you to pass a function as an argument to the method, like this: `arr.map(fn => fn(100))`.

**Other considerations:**

*   The benchmark focuses on performance differences between `map` and `forEach`, which are likely due to the way these methods interact with JavaScript's engine.
*   It's also worth noting that in many modern browsers, `forEach` is often implemented as a loop under the hood, which can lead to performance improvements.

**Alternatives:**
For this specific benchmark, there aren't any alternatives because it's specifically comparing two common array iteration methods. However, if you were looking for alternative approaches:

*   You could use other built-in methods like `reduce()` or `every()`, which also iterate over arrays but offer different functionality.
*   For certain use cases, you might prefer to write a custom loop using `for` loops and indexing into the array.
*   In some cases, using libraries like Lodash or Ramda can provide more functional programming-friendly alternatives for array iteration.

Related benchmarks:

map vs foreach for the millionth time (version: 0)

Comparing performance of: map vs for

Created: 5 years ago by: Guest

Jump to the latest result

map

for

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):