Benchmark: for vs forEach vs for in vs for of vs lodash

HTML Preparation code:

<script src="https://cdn.jsdelivr.net/npm/lodash@4.17.15/lodash.min.js"></script>

Script Preparation code:

var arr = [];

function doMath(a) {
  return Math.log(a);
}

for(i=0; i<10000; i++){
  arr[i] = i + 1;
}

Tests:

forEach
let sum = 0; arr.forEach((value) => { sum += doMath(value); });
for in
let sum = 0; for(const index in arr) { sum += doMath(arr[index]); }
for
let sum = 0; for(var i = 0; i < arr.length; i++) { const value = arr[i]; sum += doMath(value); }
for of
let sum = 0; for(const value of arr) { sum += doMath(value); }
lodash foreach
let sum = 0; _.forEach(arr, (value) => { sum += doMath(value); });

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
forEach
for in
for
for of
lodash foreach

Fastest: N/A

Slowest: N/A

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

LLMs can make mistakes. Check important info.

Let's dive into the world of JavaScript microbenchmarks.

**Benchmark Overview**

The provided benchmark tests four different methods for iterating over an array: `forEach`, `for in`, `for`, and `for of`. Additionally, it includes a fifth test case that uses Lodash's `_forEach` method. The goal is to compare the performance of each iteration method on a specific task: summing up the logarithm of each element in the array.

**Iteration Methods**

Here's a brief explanation of each iteration method:

1. **`forEach`**: This method calls a provided callback function once for each element in an array, with the current element as its argument.
2. **`for in`**: This method iterates over the properties of an object (in this case, the array's `length` property) using the prototype chain. It returns the value of each property as it is accessed.
3. **`for`**: Also known as a traditional loop, this method uses a manual index variable to access elements in an array.
4. **`for of`**: Introduced in ECMAScript 2015 (ES6), this method allows you to iterate over an array using a concise syntax that's similar to `forEach`.
5. **`lodash foreach`**: This is a custom implementation of the `forEach` method using Lodash.

**Library: Lodash**

Lodash is a popular JavaScript library that provides a lot of utility functions for tasks like array manipulation, string manipulation, and more. In this benchmark, Lodash's `_forEach` method is used to iterate over the array. Lodash provides a lot of convenience functions, but it also introduces additional overhead compared to native JavaScript methods.

**Special JS Features**

The test cases use some ES6 features:

* `for of`: This syntax was introduced in ES6 and allows for concise iteration over arrays.
* `_forEach` (Lodash): While not an officially recognized feature, this method is widely used and supported by many browsers.

**Pros and Cons**

Here's a brief summary of the pros and cons of each iteration method:

1. **`forEach`**: Pros:
	+ Concise syntax
	+ Wide browser support
Cons:
	+ May incur additional overhead due to function call
2. **`for in`**: Pros:
	+ Fast iteration (since it doesn't require function calls)
Cons:
	+ Not designed for array iteration, may lead to unexpected behavior
3. **`for`**: Pros:
	+ Fast iteration
	* Cons:
	+ Manual index management can be error-prone
4. **`for of`**: Pros:
	+ Concise syntax
	+ Modern and widely supported (since ES6)
Cons:
	+ May incur additional overhead due to function call
5. **`lodash foreach`**: Pros:
	+ Convenience function for common iteration use cases
Cons:
	+ Additional overhead due to Lodash library

**Other Alternatives**

For array iteration, some developers might consider using other libraries like:

* `Array.prototype.map()` and `Array.prototype.forEach()`: These methods provide a more functional programming style of iteration.
* `reduce()`: This method is useful for reducing an array to a single value.

In general, the choice of iteration method depends on personal preference, performance considerations, and the specific requirements of your project.

Latest run results:

Run details: (Test run date: 4 years ago)

User agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:72.0) Gecko/20100101 Firefox/72.0

Browser/OS: Firefox 72 on Ubuntu

View result in a separate tab

Test name	Executions per second
forEach	3609.1 Ops/sec
for in	473.7 Ops/sec
for	3606.0 Ops/sec
for of	3826.5 Ops/sec
lodash foreach	3683.0 Ops/sec

Related benchmarks:

for vs forEach vs for in vs for of vs lodash (version: 0)

for vs forEach vs for in vs for of vs lodash

Comparing performance of: forEach vs for in vs for vs for of vs lodash foreach

Created: 4 years ago by: Guest

Jump to the latest result

forEach

for in

for

for of

lodash foreach

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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