Benchmark: Array vs Map vs object iteration 2

Script Preparation code:

var array = []
var map = new Map()
var object = {}
for (var i = 0; i < 2000; i++) {
    array[i] = i;
    map.set(i.toString(), i);
    object[i.toString()] = i;
}
var results = []

Tests:

Array.forEach
array.forEach(i => { results.push(i * 2) })
Array for...of
for (const i of array) { results.push(i * 2) }
Map.forEach
map.forEach(i => { results.push(i * 2) })
object for...in
for (const i in object) { results.push(object[i] * 2) }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Array.forEach
Array for...of
Map.forEach
object for...in

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 benchmark measures the performance of three different iteration approaches in JavaScript: `Array.forEach`, `Array for...of`, and `Map.forEach` vs. `Object for...in`. The benchmark creates an array, a Map, and an object with 2000 elements each, and then uses these data structures to iterate over them and perform calculations.

**Iteration Approaches**

1. **Array.forEach**: This approach uses the `forEach` method of arrays in JavaScript, which iterates over the elements of an array by calling a provided callback function once for each element.
2. **Array for...of**: This approach uses the `for...of` loop with an iterator that can iterate over an array. It provides a more modern and concise way to iterate over arrays compared to traditional `forEach`.
3. **Map.forEach**: Similar to Array forEach, this approach uses the `forEach` method of Maps in JavaScript, which iterates over the key-value pairs of a Map.
4. **Object for...in**: This approach uses the `for...in` loop with an iterator that can iterate over the properties (key-value pairs) of an object.

**Comparison**

The benchmark compares the performance of these four approaches:

* **Array forEach vs. Array for...of**: The modern and concise `for...of` loop is expected to be faster than the traditional `forEach` method, as it avoids the overhead of a callback function.
* **Map forEach vs. Object for...in**: Map `forEach` is generally faster than object iteration using `for...in`, as it uses a more efficient iterator that can skip over non-enumerable properties.

**Pros and Cons**

1. **Array forEach**:
	* Pros: widely supported, easy to use.
	* Cons: slower compared to `for...of`.
2. **Array for...of**:
	* Pros: modern, concise, faster than traditional `forEach`.
	* Cons: may not be as widely supported in older browsers or JavaScript engines.
3. **Map forEach**:
	* Pros: efficient, fast, and suitable for large datasets.
	* Cons: less intuitive compared to array iteration.
4. **Object for...in**:
	* Pros: easy to understand, works well with objects.
	* Cons: slower compared to Map `forEach`, skips non-enumerable properties.

**Library Usage**

None of the test cases explicitly use any libraries, but it's worth noting that some JavaScript engines or browsers may have optimized implementations for certain methods (e.g., WebAssembly for performance-critical code).

**Special JS Features/Syntax**

The benchmark uses the `for...of` loop with an iterator, which is a modern JavaScript feature introduced in ECMAScript 2015. This loop provides a more concise way to iterate over arrays and other iterable objects.

**Alternatives**

Other alternatives for iterating over data structures include:

* **Lodash's `forEach`**: A popular utility library that provides a robust implementation of the `forEach` method.
* **Underscore.js's `forEach`**: Another popular utility library that provides a more concise implementation of the `forEach` method.
* **Manual iteration using `for` loops**: An alternative approach to iteration that uses traditional `for` loops, which can be more verbose but still effective.

In summary, the benchmark highlights the performance differences between various iteration approaches in JavaScript and encourages developers to consider the trade-offs between readability, maintainability, and performance when choosing an iteration method.

Related benchmarks:

Array vs Map vs object iteration 2 (version: 0)

Comparing performance of: Array.forEach vs Array for...of vs Map.forEach vs object for...in

Created: 6 years ago by: Guest

Jump to the latest result

Array.forEach

Array for...of

Map.forEach

object for...in

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):