Benchmark: lodash forEach vs for in 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:

foreach
var count = 0; _.forEach(values, function(v,i) { if (v.a != null) { count++; } })
for in
var count = 0; for(var value in values) { if (value.a != null) { count++; } }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
foreach
for in

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 9 months ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/138.0.0.0 Safari/537.36

Browser/OS: Chrome 138 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
foreach	55161120.0 Ops/sec
for in	20041340.0 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down the provided benchmark and explain what's being tested, the options compared, their pros and cons, and other considerations.

**What is being tested?**

The benchmark compares two approaches for iterating over an array: `lodash.forEach()` and a traditional `for` loop with `in`. The test case uses a small dataset of three objects with properties `a`, `b`, and `c`.

**Options compared:**

1. **Lodash `forEach()`**: A function that iterates over an array, executing the provided callback for each element.
2. **Traditional `for` loop with `in`**: A classic loop structure that iterates over an object's properties using the `in` operator.

**Pros and cons of each approach:**

1. **Lodash `forEach()`**
	* Pros:
		+ Concise code
		+ Easy to read and maintain
		+ Handles array iteration out-of-the-box
	* Cons:
		+ Requires an external library (lodash)
		+ May have a performance overhead due to the callback function
2. **Traditional `for` loop with `in`**
	* Pros:
		+ No external dependencies or overhead
		+ Can be faster for small datasets
	* Cons:
		+ More verbose code
		+ Requires manual management of iteration (e.g., checking for existence)

**Library: Lodash**

Lodash is a popular JavaScript library that provides a collection of functional programming helpers. In this case, the `forEach()` function is used to iterate over the `values` array.

**Special JS feature or syntax**

There are no specific features or syntax mentioned in the benchmark definition or test cases.

**Other alternatives**

For iterating over arrays, other approaches can be considered:

1. **Array.prototype.forEach()**: A built-in method that iterates over an array.
2. **Map and callback functions**: Using a `Map` object to store iteration results and applying a callback function for each value.
3. **While loops with index management**: Using a traditional `while` loop to iterate over the array, managing indices manually.

These alternatives may have different trade-offs in terms of performance, conciseness, and maintainability, but can be considered depending on the specific use case and requirements.

The benchmark result shows that Chrome 92 executes the `for in` loop faster than the `forEach()` function, but with a larger number of executions per second. This may indicate that the traditional `for` loop approach has an advantage in this particular scenario, despite being more verbose.

Related benchmarks:

lodash forEach vs for in loop (version: 0)

Comparing performance of: foreach vs for in

Created: 4 years ago by: Registered User

Jump to the latest result

foreach

for in

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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