Benchmark: Array loop vs foreach vs map vs for

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); })
for
let i = 0 let len = arr.length for (; i < len; i++) { someFn(arr[i]); }
map
arr.map(item => someFn(item))

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:

No previous run results

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

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**Benchmark Overview**

The provided JSON represents a JavaScript microbenchmarking test case created using MeasureThat.net. The benchmark tests the performance of three different approaches for iterating over an array: `forEach`, `for` loop, and `map`.

**Approaches Compared**

The benchmark compares the execution speed of these three approaches:

1. **`forEach`**: Uses the `Array.prototype.forEach()` method to iterate over the array. This approach is often used when you need to perform an action on each element of the array.
2. **`for` loop**: Uses a traditional `for` loop to iterate over the array. This approach provides fine-grained control over the iteration process, but can be less efficient than other methods for large arrays.
3. **`map`**: Uses the `Array.prototype.map()` method to transform each element of the array into a new value.

**Pros and Cons**

Here are some pros and cons associated with each approach:

* **`forEach`**:
	+ Pros: Easy to read, concise syntax, and efficient for small arrays.
	+ Cons: May not be suitable for large arrays due to its callback-based nature.
* **`for` loop**:
	+ Pros: Provides fine-grained control over the iteration process, suitable for large arrays.
	+ Cons: Can be more verbose, and the overhead of initializing variables can slow down performance.
* **`map`**:
	+ Pros: Efficient for large arrays, as it avoids the overhead of callback functions.
	+ Cons: May not be suitable for small arrays due to its transformation-based nature.

**Library and Special JS Features**

In this benchmark, no libraries are explicitly mentioned. However, `forEach` and `for` loop methods rely on the built-in `Array.prototype` object, which is a fundamental part of the JavaScript language.

**Special JS Feature**

The benchmark does not utilize any special JavaScript features, such as async/await or generators, which might affect performance in other scenarios.

**Other Alternatives**

For this specific use case, the alternatives to these approaches are:

* Instead of `forEach`, you could use `Array.prototype.forEach()` with a filter function: `arr.filter(function(item) { return someFn(item); })`.
* Instead of a traditional `for` loop, you could use an arrow function with `for...of`: `for (const item of arr) { someFn(item); }`
* Instead of `map`, you could use `Array.prototype.reduce()` or `Array.prototype.every()`.

Keep in mind that these alternatives might introduce additional overhead or changes to the code's syntax, so it's essential to consider the trade-offs when choosing an approach.

Related benchmarks:

Array loop vs foreach vs map vs for (version: 0)

Comparing performance of: foreach vs for vs map

Created: 6 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):