Benchmark: Array loop vs foreach vs map vs for ...of ...

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

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
foreach
for
map
for ... of ...

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

**Benchmark Definition**
The benchmark measures the performance of four different approaches to iterate over an array in JavaScript:

1. `Array.prototype.forEach()`
2. Traditional `for` loop
3. `Array.prototype.map()`
4. New `for...of` loop (introduced in ECMAScript 2017)

**Options Compared**

* **forEach**: Uses the `forEach()` method to iterate over the array, which calls a callback function for each element.
	+ Pros: concise and readable, can be used for both synchronous and asynchronous iterations.
	+ Cons: may incur overhead due to callback function invocation.
* **Traditional For Loop**: Uses a classic `for` loop with an index variable (`i`) to iterate over the array.
	+ Pros: efficient, predictable performance, and easy to understand.
	+ Cons: can be verbose, especially for large arrays or complex logic.
* **Map**: Uses the `map()` method to create a new array with the results of applying a given function to each element.
	+ Pros: concise, readable, and can handle asynchronous iterations.
	+ Cons: creates a new array, which may incur additional memory allocation.
* **For...Of Loop**: Uses the new `for...of` loop syntax to iterate over arrays, which is more concise than traditional `for` loops.
	+ Pros: concise, readable, and efficient.
	+ Cons: requires modern JavaScript engines (ECMAScript 2017+) for optimal performance.

**Library Usage**
None of the benchmark definitions explicitly use a library. However, some features might rely on internal engine optimizations or built-in library functions:

* `forEach()` uses the engine's built-in `forEach()` method.
* `map()` uses the engine's built-in `map()` method.
* The new `for...of` loop syntax is an ECMAScript feature introduced in 2017, so it may rely on modern JavaScript engines.

**Special JS Features or Syntax**
The benchmark uses the following features:

* **Arrow functions**: Used in the `map()` and `forEach()` definitions to provide concise, readable code.
* **Template literals**: Not used explicitly in this benchmark but are relevant for similar JavaScript constructs.

**Benchmark Preparation Code**
The script preparation code creates an array with 1000 elements and defines a simple function `someFn(i)` that takes an integer input and returns the result of multiplying it by 3 and 8.

**Other Alternatives**

* **While Loops**: An alternative to traditional `for` loops, which can be used for iterating over arrays.
* **Reduce() Method**: Can be used as an alternative to `forEach()` or `map()` for iterating over arrays, but with different use cases (e.g., reducing an array to a single value).
* **Generator Functions**: Not used in this benchmark, but can provide efficient, asynchronous iteration over large datasets.

When considering alternatives or modifications to the existing benchmark, software engineers should consider factors such as:

* Performance: What is the optimal performance characteristic for each approach?
* Readability and maintainability: Which approaches are most readable and maintainable for different developers?
* Memory usage: How do the different approaches affect memory allocation and deallocation?
* Feature support: Are there any features or libraries that would require modifications to the benchmark?

Related benchmarks:

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

Comparing performance of: foreach vs for vs map vs for ... of ...

Created: 6 years ago by: Guest

Jump to the latest result

foreach

for

map

for ... of ...

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):