Benchmark: js mapping: foreach vs for vs map

Script Preparation code:

var arr = [];
for (var i = 0; i < 10000; i++) {
    arr[i] = Math.round(Math.random(0,9999));
}

var copy1 = [], copy2 =[], copy3 = [];

Tests:

foreach
arr.forEach((el,i) => { copy1[i] = el * 3 });
for
for (var i = 0, l = arr.length; i < l; i++) { copy2[i] = arr[i] * 3; };
map
copy3 = arr.map(el => el * 3)

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
foreach
for
map

Fastest: N/A

Slowest: N/A

Latest run results:

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

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**Overview of the Benchmark**

The provided benchmark measures the performance of three different approaches for iterating over an array and performing calculations on its elements: `forEach`, `for` loop, and `map`. The test case generates a large array of random numbers, creates copies of it using each approach, and then calculates the product of each element by multiplying it with 3.

**Comparison of Approaches**

1. **forEach**: This approach uses the built-in `forEach` method, which calls a provided callback function once for each element in the array. In this test case, the callback function multiplies each element by 3 and assigns the result to the corresponding index in the copy array.
	* Pros: Concise and easy to read, as it leverages the built-in `forEach` method.
	* Cons: May be slower due to the overhead of calling a callback function for each element.
2. **for** loop: This approach uses a traditional `for` loop with an iterator variable `i`, which iterates over the array elements and assigns them to the corresponding index in the copy array.
	* Pros: Can be faster than `forEach` as it avoids the overhead of callback function calls, but may require more code to set up.
	* Cons: More verbose than `forEach`, making it less readable.
3. **map**: This approach uses the built-in `map` method, which creates a new array with the results of applying a provided transformation function to each element in the original array. In this test case, the transformation function multiplies each element by 3 and returns the result.
	* Pros: Can be faster than `forEach` as it leverages the built-in `map` method and avoids explicit loops, making it more concise.
	* Cons: May have a higher memory overhead due to creating a new array.

**Library and Special Features**

The test case uses two built-in JavaScript features:

1. **Array.prototype.forEach**: This is a built-in method that allows iterating over an array by calling a callback function for each element.
2. **Array.prototype.map**: This is another built-in method that creates a new array with the results of applying a transformation function to each element in the original array.

**Other Alternatives**

While not explicitly tested, other alternatives could be:

1. **forEach` loop (using `for...of`)**: Instead of using the `forEach` method, you can use a traditional `for...of` loop to iterate over the array elements.
2. **Lodash's `forEach`**: Lodash is a popular utility library that provides a more extensive set of functions for iterating over arrays, including a `forEach` function.
3. **Other iteration methods (e.g., `filter`, `reduce`, `every`)**: Depending on the specific use case, other iteration methods might be more suitable than `forEach`.

**Benchmarking Considerations**

When benchmarking these approaches, it's essential to consider factors such as:

* Array size and type
* Platform and browser compatibility
* Memory allocation and caching
* Garbage collection overhead

By understanding the pros and cons of each approach, developers can choose the most suitable method for their specific use case.

Related benchmarks:

js mapping: foreach vs for vs map (version: 0)

Comparing performance of: foreach vs for vs map

Created: 7 years ago by: Guest

Jump to the latest result

foreach

for

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):