Benchmark: forEach vs for i loop

HTML Preparation code:

<script src="https://cdn.jsdelivr.net/lodash/4.16.0/lodash.min.js"></script>

Script Preparation code:

var values = [{a: 30310}, {b: 100303}, {c: 3040494}]

Tests:

Array.forEach
var count = 0; values.forEach(function(v,i) { if (v.a != null) { count++; } })
native
var count = 0; for (var i = 0; i < values.length; i++) { if (values[i].a != null) { count++; } }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Array.forEach
native

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's being tested.

**Benchmark Overview**

The benchmark is designed to compare the performance of two approaches: using `Array.forEach()` and a traditional `for` loop with an index variable (`i`). The test case uses the Lodash library for array operations.

**What's Being Tested?**

The main differences between the two approaches are:

1. **Iterative style**: `forEach()` is designed to iterate over an array, while a traditional `for` loop requires manual incrementing of an index variable.
2. **Callback function vs. explicit loops**: `forEach()` uses a callback function, whereas the traditional `for` loop uses an explicit iteration with an index variable.

**Options Compared**

The two options being compared are:

1. **`Array.forEach()`**:
	* Pros: concise, readable, and efficient for iterating over arrays.
	* Cons: can be slower than traditional loops due to function call overhead.
2. **Traditional `for` loop with index variable (`i`)**:
	* Pros: can be faster than `forEach()` since it avoids function call overhead.
	* Cons: requires manual incrementing of the index variable, which can lead to errors.

**Library and Syntax Considerations**

The Lodash library is used for array operations in the benchmark. Specifically, the `forEach()` method is used to iterate over the `values` array.

There are no special JavaScript features or syntaxes being tested in this benchmark.

**Alternative Approaches**

Other alternatives could include:

1. **`Array.prototype.forEach.call()`**: This approach uses a similar callback function as `Array.forEach()`, but with the explicit call to `forEach()` on the prototype of the `values` array.
2. **Custom iteration using `reduce()` or `map()`**: Instead of using `forEach()`, one could use `reduce()` or `map()` to iterate over the array, which might have different performance characteristics.

**Benchmark Preparation Code**

The script preparation code sets up an example dataset (`values`) and includes a reference to the Lodash library. The HTML preparation code loads the Lodash library from a CDN.

**Individual Test Cases**

Each test case has a unique `Benchmark Definition` that defines the loop or function to be tested. In this case, there are two test cases:

1. **`Array.forEach()`**: Iterates over the `values` array using the `forEach()` method.
2. **Traditional `for` loop with index variable (`i`)**: Iterates over the `values` array using a traditional `for` loop.

The test results show the execution frequency per second for each browser, providing insight into performance differences between the two approaches.

Related benchmarks:

forEach vs for i loop (version: 0)

Comparing performance of: Array.forEach vs native

Created: 6 years ago by: Guest

Jump to the latest result

Array.forEach

native

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):